[PR #6605/9f47cdde backport][stable-7] New module: gitlab_merge_request.py (#6692)

New module: gitlab_merge_request.py (#6605)

* feat(gitlab_merge_request): initial module version

* feat(gitlab_merge_request): adding assignees & reviewers

* fix(gitlab_merge_request): sanity fixes

* chore(gitlab_merge_request): adding BOTMETA record

* chore(gitlab_merge_request): integration tests

* docs(gitlab_merge_request): updating modules documentation

* fix(gitlab_merge_request): proper module return values

* fix(gitlab_merge_request): remove duplicate target_branch query

* docs(gitlab_merge_request): apply improvements suggested from code review

Co-authored-by: Felix Fontein <felix@fontein.de>

* docs(gitlab_merge_request): updates to description and minor fixes based on code review

Co-authored-by: Felix Fontein <felix@fontein.de>

* chore(gitlab_merge_request): add aliases file for integration tests

* fix(gitlab_merge_request): use with syntax for IOErrors handling

Co-authored-by: Léo GATELLIER <26511053+lgatellier@users.noreply.github.com>

* fix(gitlab_merge_request): inverted message parameters

* refactor(gitlab_merge_request): use shared find_project method

* refactor(gitlab_merge_request): use username filter for user retrieval

* fix(gitlab_merge_request): handling of empty user search result

* test(gitlab_merge_request): extends integration tests suite for merge request changes

* chore(gitlab_merge_request): sanity validation & licensing fixes

* docs(gitlab_merge_request): formatting changes to documentation

Co-authored-by: Felix Fontein <felix@fontein.de>

* chore(gitlab_merge_request): licensing of test files fixed

Co-authored-by: Felix Fontein <felix@fontein.de>

* docs(gitlab_merge_request): extends description & adds code comments

---------

Co-authored-by: Felix Fontein <felix@fontein.de>
Co-authored-by: Léo GATELLIER <26511053+lgatellier@users.noreply.github.com>
(cherry picked from commit 9f47cdde32)

Co-authored-by: Ondrej Zvara <zvara.ondrej@gmail.com>

.github/BOTMETA.yml

@@ -532,6 +532,8 @@ files:
     notify: jlozadad
   $modules/gitlab_branch.py:
     maintainers: paytroff
+  $modules/gitlab_merge_request.py:
+    maintainers: zvaraondrej
   $modules/gitlab_project_variable.py:
     maintainers: markuman
   $modules/gitlab_instance_variable.py: