Improve bot logic to enable dry runs

[IsabelParedes]

It would be very useful to have an option to build packages or bump versions without opening any PRs or having to merge to main first.

Problem

When updating the bot logic to bump versions for example, this is not tested in the CI of the pull request and it should be. But some of the bot actions include merging and opening PRs.

Solution

• Add a --dry-run option for the bot. If the dry-run option is true, then instead of
  • merging a PR, print a statement [DRY RUN] Merging #XYZ or something similar
  • creating new branches, print [DRY RUN] Create branch <branch-name>
  • opening a PR, print [DRY RUN] Opening PR <pr-title> and reset changes
• Update workflows so that they are triggered during a PR which has changes in emci/ and only run the workflow with the --dry-run option enabled