ci(pr-convention-checks): add job to check for linked issues for pull requests

[SanchithHegde]

Type of Change

• Bugfix
• New feature
• Enhancement
• Refactoring
• Dependency updates
• Documentation
• CI/CD

Description

This PR adds a new pull request CI check to ensure that all pull requests have at least one linked issue.

However, GitHub does not send any webhooks when a pull request is linked with an issue, so the check does not get triggered automatically when an issue is linked for a pull request which is already open. One way to trigger it manually is to update either the pull request title or description/body, and another is to push commits. Since pushing new commits tends to trigger all other checks, editing the pull request description might be preferable in such scenarios.

In addition, the PR includes the following changes:

• Renames the conventional-commit-check.yml workflow file to pr-convention-checks.yml.
• Removes the workflow code that labelled pull requests whose titles didn't follow conventional commit standards, since we no longer use the label for any purpose nowadays. It was initially added as a means to filter pull requests by that label, when we introduced the check.

The pull request can be reviewed one commit at a time for better understanding.

Motivation and Context

Closes #3375.

How did you test it?

Temporarily modified the trigger to be pull_request instead of pull_request_target to test the workflow.

1. The check fails if the PR does not contain any linked issues.

   

   Link to check run: https://github.com/juspay/hyperswitch/actions/runs/7561263548/job/20589130650?pr=3376

2. The check succeeds if the PR contains at least one linked issue.

   

   Link to check run: https://github.com/juspay/hyperswitch/actions/runs/7561509816/job/20589902417?pr=3376

3. The check fails if any of the linked issues is closed.

   

Checklist

• I formatted the code cargo +nightly fmt --all
• I addressed lints thrown by cargo clippy
• I reviewed the submitted code
• I added unit tests for my changes where possible
• I added a CHANGELOG entry if applicable