[TS] Fix getFullyQualifiedName codegen for typescript (#7730)

#7451 caused getFullyQualifiedName to return a name with underscores,
not periods. Because the fully qualified name is a property of
FlatBuffers, not the language being codegen'd for, it should use
periods. Fixes #7564.

Co-authored-by: Derek Bailey <derekbailey@google.com>

tests/ts/reflection/schema.js

@@ -85,7 +85,7 @@ export class Schema {
         return offset ? this.bb.__vector_len(this.bb_pos + offset) : 0;
     }
     static getFullyQualifiedName() {
-        return 'reflection_Schema';
+        return 'reflection.Schema';
     }
     static startSchema(builder) {
         builder.startObject(8);