Request New API: get the current opened pull request by base and head

[lchrennew]

• Gitea version (or commit ref): 1.14.3
• Git version:
• Operating system:
• Database (use [x]):
  • PostgreSQL
  • MySQL
  • MSSQL
  • SQLite
• Can you reproduce the bug at https://try.gitea.io:
  • Yes (provide example URL)
  • No
• Log gist:

Description

For comparing page, I need an API to fetch the opened PR by the base branch and the head branch.
The request will look like this:

GET /repos/{owner}/{repo}/pulls/{base}/{head}?state=open

and the response:

200 when the PR exists, and the body is the PullRequest
404 when the PR doesn't exist

Screenshots