[Feature Request]: Have refresh timestamp on the subscriptions page update on an interval

### Guidelines

- [X] I have searched the issue tracker for [open](https://github.com/FreeTubeApp/FreeTube/issues?q=is%3Aopen+is%3Aissue) and [closed](https://github.com/FreeTubeApp/FreeTube/issues?q=is%3Aissue+is%3Aclosed) issues that are similar to the feature request I want to file, without success.
- [X] I have searched the [documentation](https://docs.freetubeapp.io/) for information that matches the description of the feature request I want to file, without success.
- [X] This issue contains only one feature request.

### Problem Description

Sometimes I leave FreeTube on in the background and like to see how long it's been since my last refresh. The problem is that the top bar doesn't refresh with the newest relative timestamp, so I have to switch to a new tab and back again to see the updated timestamp.

### Proposed Solution

Using `setInterval`, have the refresh widget timestamp update on an interval. Some questions that could take this feature into different directions:
1. How long should the interval be (e.g., 1 minute, 5 minutes)?
2. Do we update the video / live / short / community post timestamps on that interval too for consistency?

My thoughts:
1. 1 minute (makes sense, as the main discernible visual unit for the first hour, that it update on that basis)
2. No, I think if it's just the refresh timestamps, that makes sense on it's own. I don't think we want to violate the long-standing idea of these timestamps being unchanging as of first load, especially when we don't do the same behavior on other views.

### Alternatives Considered

- Different answer for 1 and/or 2
- Don't implement this feature

### Issue Labels

ease of use improvement, improvement to existing feature

### Additional Information

_No response_