std: update std.builtin.Type fields to follow naming conventions

The compiler actually doesn't need any functional changes for this: Sema
does reification based on the tag indices of `std.builtin.Type` already!
So, no zig1.wasm update is necessary.

This change is necessary to disallow name clashes between fields and
decls on a type, which is a prerequisite of #9938.

lib/docs/wasm/Walk.zig

@@ -36,7 +36,7 @@ pub const Category = union(enum(u8)) {
     /// A function that returns a type.
     type_function: Ast.Node.Index,
 
-    pub const Tag = @typeInfo(Category).Union.tag_type.?;
+    pub const Tag = @typeInfo(Category).@"union".tag_type.?;
 };
 
 pub const File = struct {

lib/docs/wasm/markdown/Document.zig

@@ -170,7 +170,7 @@ pub fn ExtraData(comptime T: type) type {
 }
 
 pub fn extraData(doc: Document, comptime T: type, index: ExtraIndex) ExtraData(T) {
-    const fields = @typeInfo(T).Struct.fields;
+    const fields = @typeInfo(T).@"struct".fields;
     var i: usize = @intFromEnum(index);
     var result: T = undefined;
     inline for (fields) |field| {

lib/docs/wasm/markdown/Parser.zig

@@ -1564,7 +1564,7 @@ fn parseInlines(p: *Parser, content: []const u8) !ExtraIndex {
 }
 
 pub fn extraData(p: Parser, comptime T: type, index: ExtraIndex) ExtraData(T) {
-    const fields = @typeInfo(T).Struct.fields;
+    const fields = @typeInfo(T).@"struct".fields;
     var i: usize = @intFromEnum(index);
     var result: T = undefined;
     inline for (fields) |field| {