hgweb: remove wsgirequest (API)
Good riddance.
.. api::
The old ``wsgirequest`` class for handling everything WSGI in hgweb
has been replaced by separate request and response types. Various
high-level functions in the hgweb WSGI applications now receive
these new types as arguments instead of the old ``wsgirequest``
type.
Differential Revision: https://phab.mercurial-scm.org/D2832
