[reorg]: Set up and populate the internal directory

Move "internal" crates into the `internal` directory. This first batch
includes most of sixtyfps_runtime but leaves the rendering backends
alone for now.

pre-commit applied some cleanups to the moved files:
 - Consistent newline at end of file policy
 - trimming trailing whitespace
 - Formatting Cargo.toml files.

internal/compiler/widgets/common/common.60

@@ -0,0 +1,105 @@
+// Copyright © SixtyFPS GmbH <info@sixtyfps.io>
+// SPDX-License-Identifier: (GPL-3.0-only OR LicenseRef-SixtyFPS-commercial)
+
+import { StyleMetrics, ScrollView } from "sixtyfps_widgets_impl.60";
+
+export LineEditInner := Rectangle {
+    callback accepted(string);
+    callback edited(string);
+    property <string> placeholder-text;
+    property font-size <=> input.font-size;
+    property text <=> input.text;
+    property placeholder-color <=> placeholder.color;
+    property enabled <=> input.enabled;
+    property has-focus <=> input.has-focus;
+    min-height: input.preferred-height;
+    min-width: max(50px, placeholder.min-width);
+    clip: true;
+    forward-focus: input;
+    input := TextInput {
+        property <length> computed_x;
+        x: min(0px, max(parent.width - width, computed_x));
+        width: max(parent.width, preferred-width);
+        height: 100%;
+        color: enabled ? StyleMetrics.textedit-text-color : StyleMetrics.textedit-text-color-disabled;
+        cursor-position-changed(cpos) => {
+            if (cpos.x + computed_x < StyleMetrics.layout-padding) {
+                computed_x = - cpos.x + StyleMetrics.layout-padding;
+            } else if (cpos.x + computed_x > parent.width - StyleMetrics.layout-padding) {
+                computed_x = parent.width - cpos.x - StyleMetrics.layout-padding;
+            }
+        }
+        accepted => { root.accepted(self.text); }
+        edited => { root.edited(self.text); }
+        vertical-alignment: center;
+        single-line: true;
+    }
+    placeholder := Text {
+        height: 100%; width: 100%;
+        vertical-alignment: center;
+        text: root.text == "" ? root.placeholder-text : "";
+    }
+}
+
+export TextEdit := ScrollView {
+    property <length> font-size <=> input.font-size;
+    property <string> text <=> input.text;
+    has-focus <=> input.has-focus;
+    enabled <=> input.enabled;
+    property <TextWrap> wrap <=> input.wrap;
+    callback edited(string);
+    forward-focus: input;
+
+    horizontal-stretch: 1;
+    vertical-stretch: 1;
+
+    viewport-width: wrap == TextWrap.word-wrap ? root.visible-width : max(root.visible-width, input.preferred-width);
+    viewport-height: max(self.visible-height, input.preferred-height);
+
+    Rectangle {
+        background: enabled ? StyleMetrics.textedit-background : StyleMetrics.textedit-background-disabled;
+    }
+
+    input := TextInput {
+        edited => { root.edited(self.text); }
+        color: enabled ? StyleMetrics.textedit-text-color : StyleMetrics.textedit-text-color-disabled;
+        single-line: false;
+        wrap: word-wrap;
+        cursor-position-changed(cpos) => {
+            if (cpos.x + viewport-x < StyleMetrics.layout-padding) {
+                viewport-x = min(0px, max(parent.visible-width - width,  - cpos.x + StyleMetrics.layout-padding ));
+            } else if (cpos.x + viewport-x > parent.visible-width - StyleMetrics.layout-padding) {
+                viewport-x = min(0px, max(parent.visible-width - width,  parent.visible-width - cpos.x - StyleMetrics.layout-padding ));
+            }
+            if (cpos.y + viewport-y < StyleMetrics.layout-padding) {
+                viewport-y = min(0px, max(parent.visible-height - height,  - cpos.y + StyleMetrics.layout-padding ));
+            } else if (cpos.y + viewport-y > parent.visible-height - StyleMetrics.layout-padding - 20px) {
+                // FIXME: font-height hardcoded to 20px
+                viewport-y = min(0px, max(parent.visible-height - height,  parent.visible-height - cpos.y - StyleMetrics.layout-padding - 20px));
+            }
+        }
+    }
+}
+
+export AboutSixtyFPS := Rectangle {
+    VerticalLayout {
+        padding: 12px;
+        spacing: 8px;
+        alignment: start;
+        Text {
+            text: "Made with";
+            font-size: 24px;
+            font-weight: 700;
+            horizontal-alignment: center;
+        }
+        Image {
+            source: @image-url("sixtyfps_logo.svg");
+            preferred-width: 128px;
+        }
+        Text {
+            text: "Version 0.2.0\nhttps://sixtyfps.io/";
+            font-size: 10px;
+            horizontal-alignment: center;
+        }
+    }
+}

internal/compiler/widgets/common/sixtyfps_logo.svg.license

@@ -0,0 +1,3 @@
+Copyright © SixtyFPS GmbH <info@sixtyfps.io>
+
+SPDX-License-Identifier: CC-BY-ND-4.0

internal/compiler/widgets/common/standardbutton.60

@@ -0,0 +1,20 @@
+// Copyright © SixtyFPS GmbH <info@sixtyfps.io>
+// SPDX-License-Identifier: (GPL-3.0-only OR LicenseRef-SixtyFPS-commercial)
+
+import { StyleMetrics, Button } from "sixtyfps_widgets_impl.60";
+
+export StandardButton := Button {
+    property <StandardButtonKind> kind;
+    text:
+        kind == StandardButtonKind.ok ? "OK" :
+        kind == StandardButtonKind.cancel ? "Cancel" :
+        kind == StandardButtonKind.apply ? "Apply" :
+        kind == StandardButtonKind.close ? "Close" :
+        kind == StandardButtonKind.reset ? "Reset" :
+        kind == StandardButtonKind.help ? "Help" :
+        kind == StandardButtonKind.yes ? "Yes" :
+        kind == StandardButtonKind.no ? "No" :
+        kind == StandardButtonKind.abort ? "Abort" :
+        kind == StandardButtonKind.retry ? "Retry" :
+        kind == StandardButtonKind.ignore ? "Ignore" : "";
+}