[4.2] Fix SubViewport physics picking

[Sauermann]

Apply the logic of handle_input_locally for physics picking (as done in #77730).

resolve in 4.2 issue #84258

For master I consider #77926 the better approach, but in order to not break compatibility in 4.2, I consider this a viable option to fix this in 4.2.

[AThousandShips]

Also considering this copies the code from #77730 I'd say a co-author would be appropriate (it's the same code in a different place)

[Sauermann]

Initially this code-section was introduced by reduz in #37317:
https://github.com/godotengine/godot/blame/d76c1d0e516fedc535a2e394ab780cac79203477/scene/main/viewport.cpp#L3657-L3673
Also the style with the multiple break; conditionals comes from that PR.

Please let me know, if I should add reduz as co-author. I'm not yet very familiar with when to use co-author.

[AThousandShips]

Then no need for co-author IMO, thought the other PR introduced this specific code

I'd suggest compressing the code regardless of the other blocks but it's either way 🙂

[akien-mga]

Thanks!