1. move "internal-lfs" route mock to "common-lfs"
2. fine tune tests
3. fix "realm" strings, according to RFC:
https://datatracker.ietf.org/doc/html/rfc2617:
* realm = "realm" "=" realm-value
* realm-value = quoted-string
4. clarify some names of the middlewares, rename `ignXxx` to `optXxx` to
match `reqXxx`, and rename ambiguous `requireSignIn` to `reqGitSignIn`