ENH: add end and end_day origin for resample
- [x] closes #37804
- [x] tests added / passed
- [ ] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

I have revert the backward arg and only add the end and end_day.
Could u take a look at this? Thanks! @jreback  Do u think it's worthwhile to explain more about these two backward resample method in ENH of whatsnew (maybe two examples added)? Probably good to add to `timeseries.rst#use-origin-or-offset-to-adjust-the-start-of-the-bins` explaining the new options ok failures unrelated Now I change it to the following format.
```
origin : {{'epoch', 'start', 'start_day', 'end', 'end_day'}}, Timestamp
    or str, default 'start_day'
    The timestamp on which to adjust the grouping. The timezone of origin
    must match the timezone of the index.
```
Will this be wrongly rendered to this?

**origin : {{'epoch', 'start', 'start_day', 'end', 'end_day'}}, Timestamp**
            or str, default 'start_day' The timestamp on which to adjust the grouping. The timezone of origin must match the timezone of the index.

Instead of:

**origin : {{'epoch', 'start', 'start_day', 'end', 'end_day'}}, Timestamp or str, default 'start_day'**
            The timestamp on which to adjust the grouping. The timezone of origin must match the timezone of the index.

@jreback  thanks @GYHHAHA 