Fix filtering of push notifications

What does this mr do?

Within request_table.js the selection of filters in the filters.html document is/was used to filter on a number of factors. Instead of this filter working, it instead let some request table updates through even though it should not have. I suspect that this only happened for those who put on an 'assigned to' filter. This filter was not yet implemented in the inFilter function.

Actions taken to fix bug

The 'assigned to' filter was implemented in request_table.js and some clean up was done to ensure better maintainability of this piece of code in the future.

Does this MR meet the acceptance criteria?

• I have added a changelog entry to reflect the significant changes I made and the bug I fixed.
• A test was created to test the bug.
• I have updated the documentation accordingly.
• I adhere to the style guide.

Closes #90 (closed)