Support multiple dotted sections in mssql schema names

Support multiple dotted sections in mssql schema names

Refined the logic used by the SQL Server dialect to interpret multi-part
schema names that contain many dots, to not actually lose any dots if the
name does not have bracking or quoting used, and additionally to support a
"dbname" token that has many parts including that it may have multiple,
independently-bracketed sections.

This fix addresses #5364 to some degree but probably does not
resolve it fully.

References: #5364
Fixes: #5366
Change-Id: I460cd74ce443efb35fb63b6864f00c6d81422688