typing: add type hints to the `charencode` module...
typing: add type hints to the `charencode` module
Since this module is dynamically imported from either `mercurial.pure` or
`mercurial.cext`, these hints aren't detected in `mercurial.encoding`, and need
to be imported directly there during the type-checking phase. This keeps the
runtime selection via the policy config in place, but allows pytype to see these
as functions with proper signatures instead of just `Any`. We don't attempt to
import the `mercurial.cext` version yet because there's no types stubs for that
module, but this will get the ball rolling.
I thought this would spill over into other modules from there, but the only two
*.pyi files that changed were for `encoding` and `charencode`. Applying this to
other dynamically selected modules will clean some things up in other files, so
this is a start. I had originally redefined the functions in the type-checking
block (like some of the `os.path` aliasing in `mercurial.util`), but this is
better because we won't have another duplication of the definitions that may get
out of date.
