feat: add ability to take action on a MR depending on various setttings

[jippi]

actions:
  - name: Close ticket if older than 45 days
    if: merge_request.time_since_last_commit > duration("45d")
    then:
      - action: close
      - action: comment
        message: "This Merge Request is older than 45 days and will be closed"

supported actions are:

• close to close the MR
• comment to add a comment to the MR
  • expects a message field with the body of the message
• reopen to reopen the MR
• discussion_locked to disable discussions on the MR
• discussion_unlocked to enable discussions on the MR

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 53 lines in your changes are missing coverage. Please review.

Project coverage is 0.00%. Comparing base (ca1bb19) to head (1a27f2a).
Report is 5 commits behind head on main.

Files	Patch %	Lines
cmd/shared.go	0.00%	24 Missing ⚠️
pkg/scm/gitlab/context_merge_request.go	0.00%	17 Missing ⚠️
pkg/stdlib/renamer.go	0.00%	5 Missing ⚠️
pkg/scm/types.go	0.00%	4 Missing ⚠️
pkg/config/config.go	0.00%	2 Missing ⚠️
pkg/config/label.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main      #8   +/-   ##
=====================================
  Coverage   0.00%   0.00%           
=====================================
  Files         20      20           
  Lines        730     730           
=====================================
  Misses       730     730           

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