Allow for partial username searches separated by spaces

Problem Definition

The autocomplete/suggest logic used when searching for users (@mention autocompletes, user pickers, etc..) only works when the exact string searched is part of the result.

For example:
Target user to be searched for is named "Testing Username".

Searching for a phrase like "Test User" wouldn't work, because this exact phrase is not contained within the target string "Testing Username".

Suggested Solution

Users would like to expand the search functionality to utilize spaces as a separator for the search string, and search multiple values/tokens against the target name.

For example:
Target user to be searched for is named "Testing Username".

Searching for "Test User" results in two phrases to search for, "Test", and "User", both of which would result in match if used in current logic.