Implement missing offset comparison methods
- [ ] closes #xxxx
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Not sure if it closes #8386, but its most of the way there.

Fix some missing comparisons, including Timedelta with Tick and Tick with (timedelta|Timedelta|Week)

Attach correct names for comparison methods.

If we can resolve #18510, we can make `Week(weekday=None)` just return a `Tick`, avoid some special casing.