Add `--actions` flag to `gh browse`

Describe the feature or problem you’d like to solve

As per #12091, someone wants to jump to https://github.com/cli/cli/actions (repo equivalent).

Proposed solution

Add --actions flag to gh browse.

Additional context

I thought about whether this should go under workflows but it's not quite semantically the same as workflows list. We could do gh workflows --web but tbh that's a bigger departure than the current gh browse command.