Add overload for ColumnCollection.get(col, default)

Add overload for ColumnCollection.get(col, default)

### Description
Fixes #11328 by adding an overload to ColumnCollection when a non-None default is provided.

### Checklist
This pull request is:

- [ ] A documentation / typographical / small typing error fix
	- Good to go, no issue or tests are needed
- [x] A short code fix
	- please include the issue number, and create an issue if none exists, which
	  must include a complete example of the issue.  one line code fixes without an
	  issue and demonstration will not be accepted.
	- Please include: `Fixes: #<issue number>` in the commit message
	- please include tests.   one line code fixes without tests will not be accepted.
- [ ] A new feature implementation
	- please include the issue number, and create an issue if none exists, which must
	  include a complete example of how the feature would look.
	- Please include: `Fixes: #<issue number>` in the commit message
	- please include tests.

Closes: #11329
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/11329
Pull-request-sha: 32db849e0df1db357df79df3a0dc2263a755d04e

Change-Id: I8bef91c423fb7048ec8d4a7c99f70f0b1588c37a