formal: fix and imrovement rollup

[GeorgeSapkin]

• Allow passing optional repo path to simplify local formality script use.
• Suggest users to provide feedback in case of issues by linking the actions repo at the top of the output and at the bottom of the summary comment.
• Check committer email for GitHub noreply address.
• Exclude dependabot commits by default from the same formality checks as Weblate.
• Fix the formal-this-repo event trigger to allow posting comments to PRs
  from forks.

Dependabot exclusions enabled (default):

Checking subject:
CI: Bump actions/upload-artifact from 5 to 6
[warn] Commit subject line exception: authored by dependabot
[warn] Commit subject line length exception: authored by dependabot

Checking body:
Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 5 to 6.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](https://github.com/actions/upload-artifact/compare/v5...v6)

[warn] Commit body line 1 is longer than 75 characters (is 88):
Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 5 to 6.
[warn] `Signed-off-by` exception: authored by dependabot
[pass] A commit message exists
=== Done checking commit '2653a6e072af1574a0d98dd4c4bb4cf4fcdb3b1f'

Dependabot exclusions disabled:

[warn] Author name (dependabot[bot]) seems to be a nickname or an alias
[pass] Committer name (George Sapkin) seems OK
[fail] Author email cannot be a GitHub noreply email
[pass] Committer email is not a GitHub noreply email

Checking subject:
CI: Bump actions/upload-artifact from 5 to 6
[fail] First word after prefix in subject should not be capitalized
[pass] Commit subject length: recommended max 50, required max 60 characters

Checking body:
Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 5 to 6.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](https://github.com/actions/upload-artifact/compare/v5...v6)

[warn] Commit body line 1 is longer than 75 characters (is 88):
Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 5 to 6.
[fail] `Signed-off-by` is missing or doesn't match author (should be `Signed-off-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>`)
[pass] `Signed-off-by` email is not a GitHub noreply email
[pass] A commit message exists

Fixes: 1079ad9 ("formal: post summary to the PR")
Fixes: 6d06d51 ("formal-this-repo: post results to the PR")

Related:

• CI: Bump tj-actions/changed-files from 47.0.0 to 47.0.1 #74
• CI: Bump actions/cache from 4 to 5 #75
• CI: Bump actions/upload-artifact from 5 to 6 #76
• CI: Bump actions/download-artifact from 6 to 7 #77