ENH: implement non-nano Timedelta scalar
- [ ] closes #xxxx (Replace xxxx with the Github issue number)
- [ ] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [ ] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [ ] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

Not user-exposed.  This is just enough to allow us to have non-nano TimedeltaArray.

asvs for tslibs.timedelta unchanged

@WillAyd thoughts on troubleshooting non-Mac build failures at import-time `ImportError: [...]/pandas/_libs/tslibs/timedeltas.cpython-38-x86_64-linux-gnu.so: undefined symbol: pandas_datetime_to_datetimestruct`

So far i've determined that yelling "but it isn't undefined" at the screen doesn't help. I think you need to modify setup.py so that timedeltas includes the header file np_datetime.h during compilation.  Err sorry undefined symbol is a runtime error, so not a matter of include but rather a linkage error. Try adding `"sources": ["pandas/_libs/tslibs/src/datetime/np_datetime.c"],` in setup.py to the appropriate timedeltas.pyx entry OK, adding np_datetime.c in setup.py for timedeltas's "sources" tentatively helps @jreback gentle ping here and #46397, lots more to do along both lines