Frontend: Add hasMergeRequest filter to VulnerabilityReport

Why are we doing this work

Following the completion of Backend: Add hasMergeRequest filter to Vulnerab... (#371313 - closed) we can add Has Merge Request into the vulnerability report's activity filter menu.

Design: &7883 (closed)

GraphQL API to use:

• https://docs.gitlab.com/ee/api/graphql/reference/#queryvulnerabilities
• !131649 (merged)

Relevant links

Non-functional requirements

• Documentation:
• Feature flag:
• Performance:
• Testing:

Implementation plan

Verification steps