Search issues in graphQl by milestone and assignees

What does this MR do?

It adds support to graphQL API for filtering issues by milestones (milestone_title) and assignees (asisgne_username, assignee_id)

GraohQL query example

project(fullPath: "flightjs/flight") {
  name
  issues(state: opened, milestoneTitle: "Sprint", assigneeId: "none") {
    edges {
      node {
        iid
        title
      }
    }
  }
}

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.

This is backend part of #197227 (closed)

changed milestone to %12.9

added [deprecated] Accepting merge requests backend bugperformance devopsplan frontend groupproduct planning milestones workflowin dev labels

added 1 commit

• 6ed6b8be - Seach issues in graphQl by milestone and assignees

Compare with previous version

Reviewer roulette

Changes that require review have been detected! A merge request is normally reviewed by both a reviewer and a maintainer in its primary category (e.g. frontend or backend), and by a maintainer in all other categories.

To spread load more evenly across eligible reviewers, Danger has randomly picked a candidate for each review slot. Feel free to override this selection if you think someone else would be better-suited, or the chosen person is unavailable.

To read more on how to use the reviewer roulette, please take a look at the Engineering workflow and code review guidelines.

Once you've decided who will review this merge request, mention them as you normally would! Danger does not (yet?) automatically notify them for you.

Category	Reviewer	Maintainer
backend	Alex Ives (@alexives)	Mayra Cabrera (@mayra-cabrera)

Generated by Danger

@Andysoiron could you review, please?

assigned to @Andysoiron

added typefeature label

removed [deprecated] Accepting merge requests label

assigned to @jarka and unassigned @Andysoiron

changed the description

added 396 commits

• 6ed6b8be...885e4d44 - 395 commits from branch master
• b04796fa - Seach issues in graphQl by milestone and assignees

Compare with previous version

assigned to @Andysoiron and unassigned @jarka

approved this merge request

Thanks @jarka!

Can you do the maintainer review @mkozono?

assigned to @mkozono and unassigned @Andysoiron