Breakpoint indicator QoL

[MewPurPur]

Addresses problems 1, 2, and 6 in https://github.com/godotengine/godot/issues/65517. Haven't found a solution to 4. Also, the PR makes problem 5 a little worse. So I can't say it closes the issue.

I haven't found a way to solve the problem yet. It might require a bigger change in structure.

Also makes the breakpoint icon a little brighter when toggled on and hovered.

[MewPurPur]

(don't merge yet, found a small regression)

[KoBeWi]

(t's not even approved) (also you can mark it as draft)

[YuriSizov]

We can mark it too, I just thought MewPurPur was about to ninja-fix that regression 😛

[MewPurPur]

I was gunna, got caught up in work though~

[MewPurPur]

Reverted some of the changes, now it only addresses the horizontal discrepancy. I'm not sure how to properly fix the vertical discrepancies.

[MewPurPur]

Added the lightening for bookmarks too :)

[akien-mga]

Needs rebase to fix godot-cpp build.

[akien-mga]

Thanks!