[feat] Enable cppcheck on GH Actions CI

[patricklodder]

follow-up from #2625

Feature Request

Manual runs of the static analysis tool cppcheck finds different (but important) issues with the code than our current CodeQL integration finds. It may make sense to use this on the CI with every PR to detect and gate the introduction of issues into the codebase.

Preferred Solution

A GH Actions check for 1.14, that automatically flags up newly introduced errors, preferably integrating an existing Actions template (like CodeQL) rather than a bespoke process, but it can of course be a bespoke process if there is no suitable template for this.

Pros:

• Detect more potential issues before merge

Cons:

• Adds pressure to the time it takes for the CI to run on each PR
• Adds maintenance cost

See #2625 for a preliminary discussion of the pros and cons.

[patricklodder]

I have dug into this a bit more.

• Bedzior/run-cppcheck is probably the simplest GH Actions implementation around and that's why it works pretty well with our source.
• I have found no off-the-shelf action that allows a comparison between a base branch and a PR, like CodeQL does.
• If we want to have Code Scanning Alerts integrations, we'll probably have to integrate that ourselves too.

Next step is to see if there are any good Actions out there that allow the second and third bullet points. If we can do a mashup and get at least either of these, so that we can track the result delta for each PR, I think this may be worth it.