Build ChorusMergeModule (and ChorusHubInstaller?)

When we moved the build to GitHub Actions building the ChorusMergeModule and ChorusHubInstaller was accidentally left out.

We should add building the ChorusMergeModule to dotnet.yml and save it as an artifact.

Also check if the ChorusHubInstaller is still needed - in a discussion on slack it was noted:

Looks like ChorusHub was last released for Windows in 2018 and the most recent successful TC build was in 2017. I don't know what the current process is, if any.
getting rid of build/ may be safe. After so much bit rot, it may be easier to rewrite the installer from scratch if we need to.

However, it seems that ChorusMergeModule.msm and ChorusHubInstaller.msi got build as part of the regular builds (targets Installer ChorusHubInstaller).

Check build/Chorus.proj prior to commit e7ab5bcca7ae571374eb9c8d742a1975aec453f3 and TC for how it was done in the past.

ToDo

• Add building ChorusMergeModule to dotnet.yml
• Is ChorusHubInstaller still needed/used by anyone?
• If it is, add building ChorusHubInstaller to dotnet.yml
• document (e.g. in dotnet.yml) where ChorusMergeModule (and ChorusHubInstaller) is used
  (in FieldWorks and FLEx Bridge installers)
• (nice to have) automatically stamp copyright dates on both
• Remove Build/Chorus.proj

Start with dotnet.yml and compare its build targets with build/Chorus.proj before commit e7ab5bcca7ae571374eb9c8d742a1975aec453f3 and the linked TeamCity configuration. Determine whether ChorusHubInstaller is still required, then verify the requested module and installer artifacts, usage documentation, copyright stamping, and removal of build/Chorus.proj against the checked ToDo items.