Lint commits in CI

[jwnrt]

This PR adds a script which lints commit messages for the title format and the signed-off-by line.

I'm not sure I've gotten the title format correct. Is it:

[ot] hw/opentitan: description?

Or is there an extra part for the IP block that was changed?

[ot] hw/opentitan: ot_hmac: description

If this shell script is too unreadable I don't mind it moving to Python, it's just that I don't know Python...

Fixes #1 and fixes #2

[rivos-eblot]

[ot] hw/opentitan: ot_hmac: description

We've been using the above syntax (from QEMU), that is dir1/dir2: component: description prefixed with [ot] .

[rivos-eblot]

If this shell script is too unreadable I don't mind it moving to Python, it's just that I don't know Python...

Shell seems ok for now.

I'm a bit concerned with the checkout as QEMU history is quite large (and that the public CI runners are deadly slow :-)). It is ok for now, but would it be possible to only query the log messages for all the PR commits rather than the full code base? I guess it cannot be done with actions/checkout though :-(

[jwnrt]

I think we could set an upper bound and hope that no PR goes over, say, 100 commits.

The commit hashes might be wrong in the error messages though.

[rivos-eblot]

Maybe it is possible to get the origin/destination branch (through Git Hub API) and use the git CLI to retrieve the info.

It guess that for now, it is nevertheless far better than having no lint at all, so let's merge it and we could improve it later.

[rivos-eblot]

Note: we will need some escape/bypass mechanism, such as for #116

[jwnrt]

I think committers should be able to click merge even when this job fails if they know it's okay

[jwnrt]

Alright, I changed the format to `[ot] path/name: component: description' but left the git checkout the same.

[rivos-eblot]

LGTM