gh9084_get_schema_index_parameter
closes #9084 
- new parameters are added to the end of the definition to remain backwards compatible.
- `index` defaults to `False` (not `True` as in `to_sql`) to remain backwards compatible.
- added tests

@jorisvandenbossche status?
 can you rebase / update?
 ## [Current coverage](https://codecov.io/gh/pydata/pandas/pull/12973?src=pr) is 85.23% (diff: 100%)

> Merging [#12973](https://codecov.io/gh/pydata/pandas/pull/12973?src=pr) into [master](https://codecov.io/gh/pydata/pandas/branch/master?src=pr) will decrease coverage by **0.01%**

``` diff
@@             master     #12973   diff @@
==========================================
  Files           140        140          
  Lines         50563      50568     +5   
  Methods           0          0          
  Messages          0          0          
  Branches          0          0          
==========================================
- Hits          43103      43101     -2   
- Misses         7460       7467     +7   
  Partials          0          0          
```

> Powered by [Codecov](https://codecov.io?src=pr). Last update [54ab5be...679a799](https://codecov.io/gh/pydata/pandas/compare/54ab5be78fac125ae6efcd650d8d3f418e60754d...679a79994413378b048717c6592dab52852a53b2?src=pr)
 @jorisvandenbossche status of this? closing as stale