[multitimer] Fixes #3693; Adds support for 12h alarm display

[kidneyhex]

Link: https://kidneyhex.github.io/BangleApps/?id=multitimer

Multi Timer 0.12

Changes:

• Fixes displaying timers that go past midnight for [multitimer] Timer cannot be set over the day end #3693
  • alarm.t = ms since midnight that the timer ends on; so t - currentTime goes negative if t is tomorrow morning (aka smaller than currentTime)
• Fixes uiRemove logic that's trying to clearTimeout for every timerInt2 when it should clearInterval, instead using the common method clearInt() to do it.
  • Not sure this has any effects, just noticed it by chance while debugging
• Adds support for 12h format if locale is set to that

Triggering of timers past midnight was already fixed with this: 44e2013

But timers still display as negative if they go past midnight.
Since timers can't be greater than 23:59:59, we don't need to worry about multiple days.

[kidneyhex]

Tagging original MultiTimer author: @frigis1

Let me know if you have any concerns.