Add SPID to toolbar

[smartguest]

Adds the SPID of the current connection/editor to the bottom right bar, similar to SSMS, added as part of the connection status (in it's own section though):

Images:
Default connection SPID:

Query Editor (showing editor SPID):

Non Query-Related connections/databases selected on Object Explorer:

Fixes: #229

Companion PRs:

microsoft/sqltoolsservice#2269

microsoft/sqlops-dataprotocolclient#97

[alanrenmsft]

please make sure this is only displayed when the spid is available, other providers won't have this information at the beginning. also it would be nice to adjust comments to make it more generic and allow extensions to provider their own preferred display name instead of hardcoding it to spid.

[alanrenmsft]

for example: in Postgres it is called PID.

[Charles-Gagnon]

Are we not going to allow providers to specify the text/name to display then?

[Charles-Gagnon]

@cheenamalhotra Can you take a look and make sure all the latest changes look good to you?

[EsSabtaouy]

@smartguest, @cheenamalhotra How can I integrate this solution into my ADS Program?

[cheenamalhotra]

If you're working with MSSQL provider, and you're listening to onConnectionComplete or onQueryComplete events you can read property serverConnectionId (available in azdata.proposed.d.ts) to get SPID for the connection in use.