Implement remote DML using four-part object name

[robverschoor]

T-SQL allows referencing objects in remote servers through a 4-part object name as follows: server_name.[database_name].[schema_name].object_name. Babelfish currently supports read access to remote table/views through 4-part names. However, modifying a remote table through a 4-part name is not currently supported.

Reference: https://github.com/MicrosoftDocs/sql-docs/blob/live/docs/t-sql/language-elements/transact-sql-syntax-conventions-transact-sql.md