Merge #6496

6496: Use builtin scopes more r=matklad a=georgewfraser

VSCode has added more builtin fallback scopes, so we can remove some of our fallback scopes by aligning with their conventions. 

Note that the macro scope doesn't seem to actually *work* at the moment. I have filed a bug with VSCode: microsoft/vscode#110150

Co-authored-by: George Fraser <[email protected]>

Author: bors[bot]

editors/code/package.json

@@ -957,9 +957,6 @@
             {
                 "language": "rust",
                 "scopes": {
-                    "macro": [
-                        "entity.name.function.macro.rust"
-                    ],
                     "attribute": [
                         "meta.attribute.rust"
                     ],