ENH: Support multi row inserts in to_sql when using the sqlite fallback
Currently we do not support multi row inserts into sqlite databases
when `to_sql` is passed `method="multi"` - despite the documentation
suggesting that this is supported.

Adding support for this is straightforward - it only needs us
to implement a single method on the SQLiteTable class and so
this PR does just that.

- [x] closes #29921
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry
