Admin - Requests - Add request filtering

[Frama-99]

The filters should appear to the left of the request cards (similar to Expedia's UI). They should include the following:

• request status (multi-select since there are only 6 statuses)
• member (dropdown that allows for search for a certain member)
• project (multi-select or search dropdown, depending on how many projects there are)
• date range (this month, this year, all time, etc.)

This will require backend changes to add filtering so that we're not pulling all requests in at once. Though if the filtering is getting "narrower" (e.g. originally all 6 statuses are selected, but now only one is), we might be able to use data that has already been fetched in the frontend.

Considerations also need to be made about whether we apply a filter right after a checkbox is selected, or if there should be an "apply" button.