pyproject: declare optional dependencies hg-evolve and hg-git

The goal is to be able to run

pipx install mercurial[full]

to get the equivalent of

pipx install mercurial
pipx inject mercurial hg-git hg-evolve

Same for

uv tool install mercurial[full]

which would be the equivalent of

uv tool install mercurial --with hg-git --with hg-evolve