CI: Create a job that checks for outdated libraries

[adrianhall]

Updating libraries is always a manual job.

We have three sets of solutions:

• The main library
• The template
• The samples

Create a github actions workflow called check-outdated:

• Runs dotnet-outdated on each solution.
• Reports (in the CI summary) the libraries to be updated.
• For each outdated library:
  • Determine if there is an issue titled "Update " that is open. Create one per the below spec if not. If it does exist, see if it needs updating
    • Change issue title to "Update to X.Y.Z" (where X.Y.Z is the new library version)
    • Record in the body of the issue the list of solutions/projects needing updating

This is likely to be a script - node/JavaScript scripts are fine, stored in scripts