job summary and buildonly option

[dzsquared]

This PR adds an (optional) job summary output whenever a project build is run that displays lists of errors and warnings.

New options for the action:

• skip-job-summary can be set to true to not output the job summary
• action can be set to BuildOnly to only build the dacpac and not run sqlpackage (#87)

By adding BuildOnly, the connection string parameter is no longer strictly required in all scenarios.

before or with skip-job-summary set to true:

action with SQL project file successfully building:

action with SQL project file failing during build: