Support using label names for personal repos via API

[chxseh]

Description

Similar to #30917, and #32891, the Labels API for a user repo (/repos/owner/repoName/labels/) does not let you use the name of the label (instead requiring the ID) to create/delete/update.

Ideally this would be fixed so things like label-sync can work on Gitea.

{
    "message": "The target couldn't be found.",
    "statusCode": 404,
    "body": {
        "errors": null,
        "message": "The target couldn't be found.",
        "url": "https://git.domain.com/api/swagger"
    },
    "method": "PATCH",
    "endpoint": "/repos/repoOwner/repoName/labels/bug"
}

Gitea Version

1.24.2

Can you reproduce the bug on the Gitea demo site?

No

Log Gist

No response

Screenshots

No response

Git Version

No response

Operating System

No response

How are you running Gitea?

Docker Compose

Database

MySQL/MariaDB