ENH: Allow to_sql to recognize single sql type (GH11886)
Rebase of PR https://github.com/pydata/pandas/pull/13252

Closes https://github.com/pydata/pandas/issues/11886

## [Current coverage](https://codecov.io/gh/pydata/pandas/pull/13614?src=pr) is 84.38% (diff: 100%)

> No coverage report found for **master** at 1cd1026.
> 
> Powered by [Codecov](https://codecov.io?src=pr). Last update [1cd1026...554f7e8](https://codecov.io/gh/pydata/pandas/compare/1cd1026ed7061882a05521a7c16200eadae591e4...554f7e80fd2b0a0901597c43eac0ba92a529c4c5?src=pr)
 Rebased this, @jreback or @sinhrks can you do a quick sanity check?
 lgtm.
