MAINT: Move report code

[larsoner]

Let's try this from another angle. This PR just moves mne/report.py->mne/report/report.py along with its accompanying paths and infrastructure. Then once that's done @hoechenberger you can easily overwrite and the diff should be more manageable.

@hoechenberger an easy way once this is merged (if we go this route) would be to:

git fetch upstream
git checkout main
git reset --hard upstream/main
git checkout -b report2
git checkout report mne/report/report.py mne/data/html_templates.py mne/report/__init__.py ... # all files you changed
rm mne/html/jquery.js ... # all files you deleted
git reset  # if you want to be able to see "git diff"
git commit -am 'ENH: Rework report'
git push origin -u report2

It'll only take a minute to enumerate the files changed and files deleted, so not too painful I think.

[agramfort]

thx @larsoner

CI failures are unrelated

[hoechenberger]

Thanks a bunch, @larsoner!!