[WIP, ENH] Adds cumulative methods to ea
- [x] closes #28385
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

Problem specific

- [X] Add abstract tests similar to pandas/tests/extension/base/reduce.py
- [X] Add TestFixtures for Accumulations
- [x] Implement Accumulation for IntegerArray
- [ ] Implement Accumulation for DecimalArray - out of scope
- [ ] Implement Accumulation for DatetileLikeArrayMixin ? - out of scope
- [x] Use BaseNoAccumulateTest where applicable - implemented this for categorical