Correct use of the terms filtering and search

Searching and filtering are different and have different use cases. We should use the terms correctly, rather than simplifying to just one.

• Filtering takes a single criteria that removes items within a list that match/don't match. It also doesn't affect ordering.

• Search uses all metadata to add criteria that match/don't match. It can also affect ordering (think of when searching for a user within the author filter).

• Sort orders a list based on a single criteria.

We use filter incorrectly in some cases on GitLab. For example, searching by commit message says filter, but it is actually a search