Introduce RequestContext: is a short-lived context that is used to store
request-specific data.
RequestContext could be used to clean form tmp files, close context git
repo, and do some tracing in the future.
Then a lot of legacy code could be removed or improved. For example:
most `ctx.Repo.GitRepo.Close()` could be removed because the git repo
could be closed when the request is done.
1. clarify the "filepath" could(should) contain "{ref}"
2. remove unclear RepoRefLegacy and RepoRefAny, use RepoRefUnknown to guess
3. by the way, avoid using AppURL
This PR only does "renaming":
* `Route` should be `Router` (and chi router is also called "router")
* `Params` should be `PathParam` (to distingush it from URL query param, and to match `FormString`)
* Use lower case for private functions to avoid exposing or abusing
Since `modules/context` has to depend on `models` and many other
packages, it should be moved from `modules/context` to
`services/context` according to design principles. There is no logic
code change on this PR, only move packages.
- Move `code.gitea.io/gitea/modules/context` to
`code.gitea.io/gitea/services/context`
- Move `code.gitea.io/gitea/modules/contexttest` to
`code.gitea.io/gitea/services/contexttest` because of depending on
context
- Move `code.gitea.io/gitea/modules/upload` to
`code.gitea.io/gitea/services/context/upload` because of depending on
context
