Add sorting and filtering functionality to Change Request list

We should add the ability to sort, filter and search change requests in the list view in a given environment.

Sort should be possible by:

1. created date asc / desc
2. scheduled date (for scheduled changes)
3. maybe committed date when showing already committed CRs

Filter should be possible by:

1. Author
2. Assigned user / group

Search should search across:

1. Change request title
2. Change request description
3. Any associated features / feature names