refactor: Introduce crates folder (#2088)

This PR introduces a new `crates` directory and moves all "product" crates into that folder. 

Part of #2059.

crates/ruff_cli/src/commands/linter.rs

@@ -0,0 +1,66 @@
+use itertools::Itertools;
+use serde::Serialize;
+use strum::IntoEnumIterator;
+
+use ruff::registry::{Linter, RuleNamespace, UpstreamCategory};
+
+use crate::args::HelpFormat;
+
+pub fn linter(format: HelpFormat) {
+    match format {
+        HelpFormat::Text => {
+            for linter in Linter::iter() {
+                let prefix = match linter.common_prefix() {
+                    "" => linter
+                        .upstream_categories()
+                        .unwrap()
+                        .iter()
+                        .map(|UpstreamCategory(prefix, ..)| prefix.as_ref())
+                        .join("/"),
+                    prefix => prefix.to_string(),
+                };
+
+                #[allow(clippy::print_stdout)]
+                {
+                    println!("{:>4} {}", prefix, linter.name());
+                }
+            }
+        }
+
+        HelpFormat::Json => {
+            let linters: Vec<_> = Linter::iter()
+                .map(|linter_info| LinterInfo {
+                    prefix: linter_info.common_prefix(),
+                    name: linter_info.name(),
+                    categories: linter_info.upstream_categories().map(|cats| {
+                        cats.iter()
+                            .map(|UpstreamCategory(prefix, name, ..)| LinterCategoryInfo {
+                                prefix: prefix.as_ref(),
+                                name,
+                            })
+                            .collect()
+                    }),
+                })
+                .collect();
+
+            #[allow(clippy::print_stdout)]
+            {
+                println!("{}", serde_json::to_string_pretty(&linters).unwrap());
+            }
+        }
+    }
+}
+
+#[derive(Serialize)]
+struct LinterInfo {
+    prefix: &'static str,
+    name: &'static str,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    categories: Option<Vec<LinterCategoryInfo>>,
+}
+
+#[derive(Serialize)]
+struct LinterCategoryInfo {
+    prefix: &'static str,
+    name: &'static str,
+}