CI/CD for the MSSQL database

[retailcoder]

• CI uses MSBuild on Windows to build the database project on push, using a standard GitHub-hosted runner; uploads the build asset.
• CD (test) downloads the asset and runs it on the self-hosted GitHub runner to deploy the rubberduck_testdb database on push.
• CD (prod) downloads the asset and runs it on the self-hosted GitHub runner to deploy the rubberduckdb database manually whenever the production site is deployed.

[Vogel612]

There is a community-provided SDK providing a large part of the sqlproj functionality exposing it to build processes using dotnet-cli: https://github.com/rr-wfm/MSBuild.Sdk.SqlProj