Add strong linting on PR creation.

[tomkirbygreen]

I'm cleaning stuff up only to find its being put back in so we need an automated linting check on PR creation. I'm currently looking at the ReSharper Command Line tool as an option.

┆Issue is synchronized with this Jira Task by Unito

[tomkirbygreen]

Tried running jb inspectcode IO.Ably.NetStandard.sln -o=inspection.xml and there's lot of good analysis. There are various community efforts to wrap this up as a GitHub Action, I particularly like this one that annotates your PRs:

https://github.com/glassechidna/resharper-action

[QuintinWillison]

Related to #1063.