More visible sleep timers when active

[eblis]

Description

More visible sleep timers when active, also show if sleep timer is ending this episode or not.

Make sleep timers more visible when active and change the color of the remaining time to orange (similar to the defunct Google Podcasts). Add a clock icon if the sleep timer will end before the episode finishes playback (or at the end of the episode), a minus icon if sleep timer will continue into the next episode(s).

Clock sleep timer will end before the episode does, in 13:35 minutes:

Clock sleep timer will continue to the next episode(s), there's 11:39 minutes left for this episode.

Sleep timer is disabled, reverts to showing elapsed time (always shows remaning time while sleep timer is active):

Same thing, but user selected to show remaining time:

Episode sleep timers behave the same way, here's how it looks when it ends this episode:

And how it looks if I have 2 episodes left in sleep timer:

Closes #7239

Checklist

• [x] I have read the contribution guidelines: https://github.com/AntennaPod/AntennaPod/blob/develop/CONTRIBUTING.md#submit-a-pull-request
• [x] I have performed a self-review of my code
• [x] I have run the automated code checks using ./gradlew checkstyle spotbugsPlayDebug spotbugsDebug :app:lintPlayDebug
• [x] My code follows the style guidelines of the AntennaPod project: https://antennapod.org/contribute/develop/app/code-style
• [x] I have mentioned the corresponding issue and the relevant keyword (e.g., "Closes: #xy") in the description (see https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue)
• [x] If it is a core feature, I have added automated tests