Rust: rename MatchExpr.expr to scrutinee in all layers

This doesn't require `ql.name` and is simpler while we don't have
to write upgrade scripts. The `ql.name` mechanism might get useful
once we do have to write upgrade scripts, as that doesn't change the
dbscheme.

Author: Paolo Tranquilli

rust/ast-generator/src/main.rs

@@ -28,6 +28,7 @@ fn class_name(type_name: &String) -> String {
 fn property_name(type_name: &String, field_name: &String) -> String {
     match (type_name.as_str(), field_name.as_str()) {
         ("Path", "segment") => "part".to_owned(),
+        ("MatchExpr", "expr") => "scrutinee".to_owned(),
         (_, "then_branch") => "then".to_owned(),
         (_, "else_branch") => "else_".to_owned(),
         _ => field_name.to_owned(),

rust/extractor/src/generated/.generated.list

@@ -1896,9 +1896,9 @@ match_expr_attrs(
 );
 
 #keyset[id]
-match_expr_exprs(
+match_expr_scrutinees(
   int id: @match_expr ref,
-  int expr: @expr ref
+  int scrutinee: @expr ref
 );
 
 #keyset[id]

rust/extractor/src/generated/top.rs

@@ -289,7 +289,7 @@ class _:
     }
     ```
     """
-    expr: _ | ql.name("scrutinee") | doc("scrutinee (the expression being matched) of this match expression")
+    scrutinee: _ | doc("scrutinee (the expression being matched) of this match expression")
 
 
 @annotate(ContinueExpr, cfg = True)