Make mssql extension a module (#18804)

* Rebase from main branch

* import from module

* Add mssql module ref

Co-authored-by: Charles Gagnon <chgagnon@microsoft.com>

extensions/sql-bindings/src/typings/ref.d.ts

@@ -6,5 +6,6 @@
 /// <reference path='../../../../src/vs/vscode.d.ts'/>
 /// <reference path='../../../../src/sql/azdata.d.ts'/>
 /// <reference path='../../../../src/sql/azdata.proposed.d.ts'/>
+/// <reference path='../../../mssql/src/mssql.d.ts'/>
 /// <reference path='../../../types/vscode-mssql.d.ts'/>
 /// <reference types='@types/node'/>