There were three distinct mechanisms for signaling breakpoint changes in DolphinQt, and the wiring had room for improvement. The behavior of these signals has been consolidated into the new `Host::PPCBreakpointsChanged` signal, which can be emitted from anywhere in DolphinQt to properly update breakpoints everywhere in DolphinQt.

This improves a few things:
- For the `CodeViewWidget` and `MemoryViewWidget`, signals no longer need to propagate through the `CodeWidget` and `MemoryWidget` (respectively) to reach their destination (incoming or outgoing).
- For the `BreakpointWidget`, by self-triggering from its own signal, it no longer must manually call `Update()` after all of the emission sites.
- For the `BranchWatchDialog`, it now has one less thing it must go through the `CodeWidget` for, which is a plus.

Adds the ability to hide unneeded features of the controls toolbar.

Invert conditions, invert decrement checks, and make conditional branches unconditional. USnapshotMetadata in prior versions of Dolphin is forward-compatible with these changes (tested on x86_64).

Also removed worthless `Start` and `Pause` helpers from `Core::BranchWatch`.

Giving a warning if these are used when not usable is bad UX.

The latter signal was used by mistake, see PR #8263.

m_index_list_temp should not be imagined as a member of `BranchWatchDialog`, so it is now mutable to allow for more const member functions.

Instead of one wildly complex context menu constructed lazily, now three manageable context menus are constructed proactively.

Objects which get parented automatically by later processing now pass a nullptr to the constructor to make the intent clearer. Also fixed "true" and "false" not being translatable strings.