resourceutil: don't limit resources to the `mercurial` package
This should make things a little clearer, in that it now requires the full
package name to access a resource. But the real motivation is that
`extensions._disabledpaths()` walks the `hgext` directory looking for bundled
extensions. This in turn feeds, among other things:
1) Listing disabled extensions in `hg help extensions`
2) Indicating that an unknown command is in a non-enabled extension
3) Displaying help for non-enabled extensions
4) Generating documentation
5) Announcing LFS is auto-enabled (or not) when cloning from an LFS source
The filesystem based ResourceReader will happily return *.py and *.pyc, but the
one supplied by PyOxidizer doesn't. Presumably we can change that. The only
other idea I had here is for setup.py to generate a text file containing the
list of extensions, but that doesn't seem great when running from source.
Differential Revision: https://phab.mercurial-scm.org/D7772
#require black
$ cd $RUNTESTDIR/..
$ black --config=black.toml --check --diff `hg files 'set:(**.py + grep("^#!.*python")) - mercurial/thirdparty/** - "contrib/python-zstandard/**"'`