refactor(workspace): unify table browsers into GenericTableView

[ZhuchkaTriplesix]

Summary

Unifies the duplicated table browser implementations across PostgreSQL, MySQL, SQLite, and Extension drivers into a reusable GenericTableView component and a database-specific TableDataMutationDelegate.

• Created TableDataMutationDelegate interface to abstract data fetching, custom SQL loading, schema inspection, and DML staging.
• Created GenericTableView handling pagination, in-place edit mode toggling (Ctrl/Cmd+E, F5), staging buffers (DataGridStagingBuffer), custom SQL results mode, toolbar integration, and results display.
• Refactored:
  • PostgresTableView -> PostgresTableDataDelegate + GenericTableView
  • MysqlTableView -> MysqlTableDataDelegate + GenericTableView
  • SqliteTableView -> SqliteTableDataDelegate + GenericTableView
  • ExtensionTableView -> ExtensionTableDataDelegate + GenericTableView
• Preserved existing toolbars, shortcuts, custom action dialogs (DDL, privileges, SQL editor), and custom filter bars.

Closes #1033