Allow Access to Master

It would really help with backwards compat and frustrations connecting in SSMS if Fabric SQLDB allowed users to connect to master.

This adds 2 improvements

1) In this way we could connect to SSMS and then change DB afterwards , which is very much a mainstream practice. we understand telemetry shows that this is the No1 connection error from SSMS.

2) Currently some features such as dacpac, VS package export from SSMS and 3rd party schema compares break due to this issue.