Better than before, still not good enough (more work can be done in the
future)
And add the missing error handling in the PrivateContext "bind"
middleware.
By the way, picked some "TrimSpace" changes from "fix: trim whitespace
from SMTP address and port - #38934" (fix#38926)
1. add `GetSiteCookieFlashMessage` to help to parse flash message
2. clarify `handleRepoHomeFeed` logic
3. remove unnecessary global variables, use `sync.OnceValue` instead
4. add some tests for `IsUsableUsername` and `IsUsableRepoName`
Change all license headers to comply with REUSE specification.
Fix#16132
Co-authored-by: flynnnnnnnnnn <flynnnnnnnnnn@github>
Co-authored-by: John Olheiser <john.olheiser@gmail.com>
wxiaoguang