coral(epic) - Requests pages: make entity tabs navigation links, make tabs filter by request status

# What is this about?

Currently, the "My team's requests" and "Approve request" UIs are:
- a single page
- with tabs allowing to switch between entities
- and a series of filter, including a "Status" filter


A new design proposal is to refactor this UI to make "Status" a more important part of the UI, to provide a more pleasant experience of browsing request. In that view, it would be:
- one page per entity (as sub-links of "My team's requests" and "Approve request" accordions)
- with "Status" tabs
- which would replace the "Status" filter


# Small POC

This is a proof of concept using `useFilterValue` and updating that value on clicking a `Tab`: https://github.com/aiven/klaw/pull/1104

https://user-images.githubusercontent.com/20607294/235679179-2a71c07c-96ba-4c1a-9344-e42b8e81df89.mov

# Questions to be answered

1. Should the number tag on the "Status" tab only show for the "Awaiting approval" tab? If not, what does it represent for the other tabs?
2. Should we add a number tag in the side navigation as well, to signal that there are requests to be approved for each entity?
3. How should filtering behave when switching between tabs? Keep previous filtering, or reset?
4. Should there be a way to see *all* requests? As in, all statuses together? If so, how should it be implemented?

# TODO

- [ ] Add `StatusTabs` components, possibly implementing `useFilterValue` as demonstrated in the POC.
- [ ] Implement `StatusTabs` in `ApprovalsPage` pages, update `MainNavigation` with entity links
- [ ] Implement `StatusTabs` in `RequestsPage` pages, update `MainNavigation` with entity links