templater: make open_template() read from resources if in frozen binary This takes the number of failing tests with PyOxidizer from 87 to 72. Differential Revision: https://phab.mercurial-scm.org/D8894

templater: pass opened file-like object to templatespec I think I said earlier that I planned to create a special templatespec variant for built-in templates. That was true (I planned that), but I ended up (in this patch) just adding a file-like object to the `mapfile_templatespec()` variant instead. Differential Revision: https://phab.mercurial-scm.org/D8893

templater: replace templatepath() with function that also opens the file For frozen binaries, such as those created by PyOxidizer, I plan to make it so the templatespec can keep an opened file/resource to read from instead of needing a file path. Having `templatepath()` return an opened file should help with that. At this point, it's just a wasteful extra opening of mapfiles that we'll open again later. I'll update the read-side next so it reads from the file-like object without opening the file again. Differential Revision: https://phab.mercurial-scm.org/D8892

templater: start passing resource to read from into _readmapfile() This patch makes it so we pass in a file-like resource to read from instead of having `_readmapfile()` open the file. This is one more step towards making `_readmapfile()` able to read resources opened by from `importlib.resources`. We still need to pass in the mapfile path because it's used for loading dependent mapfiles from `%include` and `__base__`, and it's also used for giving the user better error messages. Besides that, one can safely call `_readmapfile()` with any file-like resource after this patch. Differential Revision: https://phab.mercurial-scm.org/D8891

templater: move stylemap() to hgweb_mod, since that's its only user `stylemap()` even has an error message that mentions "hgweb templates", so it seems that it's meant specifically for hgweb. Differential Revision: https://phab.mercurial-scm.org/D8890

hgweb: simplify staticfile() now that we always pass it a single directory I didn't realize this further simplifications enabled by D8786 until now. Differential Revision: https://phab.mercurial-scm.org/D8874

packaging: include templates with their package as key in package_data This is similar to an earlier patch in this series. It seems more correct to use `mercurial.templates.coal` etc as keys in the `package_data` dict now that those modules are packages. Differential Revision: https://phab.mercurial-scm.org/D8858