Rename rollback_changes to undo_changes

To avoid overload with database rollback
Add String support for min/max attributes on DatetimeField
Merge pull request #15214 from todd/date_field_docs

Added String support for min and max properties for date field helpers
Use if/else

Since we are using both branches of the code is preferable to use
if/else over the early return.
Add CHANGELOG entry for #15214

Closes #15214
push host / port / protocol extraction up

Then we only need to extract host once.
Fix doc unwanted dl Admin:: [ci skip]
Merge pull request #15997 from cirosantilli/typo

Fix doc unwanted dl Admin:: [ci skip]