Enable [`forcetypeassert`](https://github.com/gostaticanalysis/forcetypeassert)
linter to prevent unchecked type assertions. ~650 issues fixed, most
fixes were clean, some use `setting.PanicInDevOrTesting`.
The only behaviour changes are where code would previously send a 500 error
or panic, a 4xx error is now emitted.
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Issue: [link](https://github.com/go-gitea/gitea/issues/9637)
Changes introduced: I have clarified the problematic terms (`login`,
`login_name`, and `username`) in all affected endpoints.
The changes were made to relevant:
- HTTP endpoint parameters' descriptions
- response/request models' fields
