Move CI to jobs in single workflow

[williamjallen]

This commit moves CI from individual workflows to a series of jobs in a single workflow. This allows jobs to share the same triggers and environment variables. This can be further simplified in a future commit by using a matrix to share common installation and build logic between jobs.

[williamjallen]

Hi @wkliao, is this change something you'd be interested in if I resolve the new conflicts? Using a matrix for these in the future would mean that you'd only have to make a single change when you want to add a flag like you did in e94f32c.

[wkliao]

Looks like using a matrix is a good way to go. Could you revise this PR?

[williamjallen]

@wkliao I just updated this PR with the most recent CI changes. This PR simply copies and pastes everything as-is into a single workflow. This means that all the jobs now share the same workflow triggers and environment variable definitions. Since this is already such a large PR, my plan is to create a series of smaller follow-up PRs to gradually reduce the amount of duplication via a matrix. Let me know if you'd like me do anything differently!

[williamjallen]

@wkliao I just rebased this on bde76b0, and added the permissions keys to the new CI file. I didn't see any reason why the pull-requests: write permission was needed, so I only set contents: read in the new file.

[wkliao]

my plan is to create a series of smaller follow-up PRs to gradually reduce the amount of duplication via a matrix.

I wonder if this PR can be modified to use the matrix approach directly, i.e. by skipping the middle changes.

[wkliao]

FYI. PR #216 uses the matrix strategy. I think that is more concise.

[williamjallen]

Closing in favor of #216.