Create dotnet tool for many of the scripts/tools in this repo

[JoeRobich]

We should empower Roslyn devs with the ability to perform more infra tasks and make it easier to get answers to common infra questions.

We can start by migrating several existing scripts/tools to run from a common tool.

Possible Subcommands

• What PRs have been merged between two commits (PR Finder) (Added Roslyn global tool with PRFinder subcommand #1170)
• Latest VS insertions (VS Branch Info) (Move VSBranchInfo to the dotnet tool, and add Razor support #1185)
• Create VS Release Tags (CreateTagsForVSRelease) (Move CreateVSReleaseTags to be Roslyn tool subcommand #1186)
• Which VS includes this PR/commit (New tool)
• Create GitHub Merge PRs
• Create VS Insertions (Roslyn Insertion Tool)

[JoeRobich]

Instead of taking this PR (#906) we should move RIT functionality to dotnet-roslyn (#1168) as a set of subcommands which correspond to various scripts create-insertion (OneOffInsertion), create-dummy-insertion (CreateDummyPR), update-insertion, & overwrite-insertion (UpdateExistingPR).

Feel free to suggest that create-dummy-insertion could be a --dummy flag on create-insertion. Or that overwrite-insertion could be an --overwrite flag on update-insertion.

[dibarbet]

Which VS includes this PR/commit (New tool)

It would be nice if we could actually tag the github PR with a linked to the merged insertion somehow (comment might be too noisy, maybe we can edit the description?)

[dibarbet]

Create VS Insertions (Roslyn Insertion Tool)

We should clean up the RIT as part of this (remove the powershell scripts, consolidate the flags where possible). For example /updateexistingpr and /overwritepr could conceivably be combined since 90% of the time we use both together

[JoeRobich]

It would be nice if we could actually tag the github PR with a linked to the merged insertion somehow (comment might be too noisy, maybe we can edit the description?)

You are talking about #1177, comment is good because it creates a notification that would alert the author or collaborators that it is available for verification. We should probably also look at linked issues and give them notice as well. vs code's github issue bot made this a very nice experience when I encountered it this week.

[JoeRobich]

We should clean up the RIT as part of this (remove the powershell scripts, consolidate the flags where possible). For example /updateexistingpr and /overwritepr could conceivably be combined since 90% of the time we use both together

RIT will no longer get updates once the roslyn-tools tool has these subcommands. We will help partner teams migrate their insertion pipelines to the new tool and archive RIT.