rhg: fix user-facing error message so it matches Python implementation

rust-ui: refactor ui code for printing narrow/sparse warnings This will be used elsewhere in the code, starting from the next commit.

rhg-files: reuse centralized dirstate logic The `files` logic predates the centralized dirstate logic. It was duplicated, an didn't receive bugfixes along the way.

rust: move `filter_map_results` to public util This is a useful general-purpose function. It will be used in the next changesets.

rhg: fix typo

run-tests: stop ignoring venv-installed packages This will allow test dependencies to be installed within a venv, instead of tampering with sys/user sites. One thing to note here is that the `VIRTUAL_ENV` path takes precedence over system-site, unlike when run directly with an activated `venv`. For example, `sys.path` as viewed from a feature test in `hghave.py`, when running `hghave vcr` directly with an activated `venv`: sys.path: [ '/home/jenkins/hg-committed/tests', '/usr/lib/python38.zip', '/usr/lib/python3.8', '/usr/lib/python3.8/lib-dynload', '/home/jenkins/test_venv/lib/python3.8/site-packages' ] vs `sys.path` from the same feature test, when run by `run-tests.py` with this change: sys.path: [ '/home/jenkins/hg-committed/tests', '/home/jenkins/hg-committed', '/home/jenkins/hg-committed/tests', '/home/jenkins/test_venv/lib/python3.8/site-packages', '/usr/lib/python38.zip', '/usr/lib/python3.8', '/usr/lib/python3.8/lib-dynload', '/home/jenkins/.local/lib/python3.8/site-packages', '/usr/local/lib/python3.8/dist-packages', '/usr/lib/python3/dist-packages' ]

fix: add more information to the debug output The previous debug output did not help to understand which file where fixed in which revision. The new output should cover that.

bundlerepo: raise `error.LookupError` instead of `LookupError` I'm pretty sure that this was the intention, given `error.LookupError` is raised a few lines above with the same arguments. Note that PyCharm complains about `self.display_id` (and the use above this too) being `() -> Any` instead of `bytes`, but it may be confused about the `util.propertycache` annotation on it.

unionrepo: resync several methods to actually override superclass methods Not sure how/when these skewed, but these were flagged by PyCharm as having different signatures.

hgweb: unbyteify the 100-continue check The environment seems to be `str` or `tuple[int]`, and the same check in `wsgicgi.py` is already `str` based, so I suspect this was wrong. I think what happened here is that the string wasn't `r''` prefixed in 482d6f6dba91 like `wsgicgi.py`, so it got wrongly byteified in 687b865b95ad when converting to byte literals en masse.