Fix a bunch of parser/formatter bugs found in fuzzing

Notably:
* Unified how parens are formatted between (1) when we have a ParensAround, and (2) when we've decided an Apply needs to have parens
* Made unary minus require the be indented to the same level as any other expression continuation. (it used to accidentally have rules meant for binary operators applied)
* Don't apply extra indent to the backpassing continuation in the case that the call does itself require indentation
* Make `try@foo` correctly parse as `try @foo`, so that formatting doesn't change the tree when it adds that space
* Detect more cases where we need to outdent trailing e.g. {} blocks in applies
* Approximately a bagillion other things, 90% of which I added tests for, and none of which affected the formatting of examples or builtins

crates/compiler/test_syntax/src/minimize.rs

@@ -102,6 +102,12 @@ fn round_trip_once(input: Input<'_>) -> Option<String> {
         return Some("Different ast".to_string());
     }
 
+    let reformatted = reparsed_ast.format();
+
+    if output != reformatted {
+        return Some("Formatting not stable".to_string());
+    }
+
     None
 }
 

crates/compiler/test_syntax/src/test_helpers.rs

@@ -239,7 +239,7 @@ impl<'a> Input<'a> {
                 self.as_str(),
                 output.as_ref().as_str(),
                 actual,
-                reparsed_ast_normalized
+                reparsed_ast
             );
         }