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/can/src/desugar.rs

@@ -1104,10 +1104,21 @@ pub fn desugar_expr<'a>(
             // Allow naked dbg, necessary for piping values into dbg with the `Pizza` binop
             loc_expr
         }
-        DbgStmt(condition, continuation) => {
+        DbgStmt {
+            first: condition,
+            extra_args,
+            continuation,
+        } => {
             let desugared_condition = &*env.arena.alloc(desugar_expr(env, scope, condition));
             let desugared_continuation = &*env.arena.alloc(desugar_expr(env, scope, continuation));
 
+            if let Some(last) = extra_args.last() {
+                let args_region = Region::span_across(&condition.region, &last.region);
+                env.problem(Problem::OverAppliedDbg {
+                    region: args_region,
+                });
+            }
+
             env.arena.alloc(Loc {
                 value: *desugar_dbg_stmt(env, desugared_condition, desugared_continuation),
                 region: loc_expr.region,

crates/compiler/can/src/expr.rs

@@ -1245,7 +1245,7 @@ pub fn canonicalize_expr<'a>(
 
             (loc_expr.value, output)
         }
-        ast::Expr::DbgStmt(_, _) => {
+        ast::Expr::DbgStmt { .. } => {
             internal_error!("DbgStmt should have been desugared by now")
         }
         ast::Expr::LowLevelDbg((source_location, source), message, continuation) => {
@@ -2546,7 +2546,7 @@ pub fn is_valid_interpolation(expr: &ast::Expr<'_>) -> bool {
         | ast::Expr::Tag(_)
         | ast::Expr::OpaqueRef(_) => true,
         // Newlines are disallowed inside interpolation, and these all require newlines
-        ast::Expr::DbgStmt(_, _)
+        ast::Expr::DbgStmt { .. }
         | ast::Expr::LowLevelDbg(_, _, _)
         | ast::Expr::Return(_, _)
         | ast::Expr::When(_, _)