fix: consolidate grammar tests into builder tests and remove backup stubs

- Delete redundant grammar test files from masoniteorm.backup (stale imports,
  sync API, duplicated by existing builder tests)
- Add delete SQL+bindings mock assertions to test_sqlite_query_builder
- Add insert SQL+bindings mock assertions to test_sqlite_builder_insert
- Add update SQL+bindings mock assertion alongside delete tests

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: tmgbedu