[avm1] Better handling of preload/suppress functions flags

[moulins]

• Handle the case where both preload aud suppress flags are set for the same variable;
• Remove arguments field in Activation; instead use a normal local definition;
• When suppress_this is set, inherit the this value from parent activation. (This isn't entirely correct, as FP's this is mutable and seems to be part of the scope chain, but this would require a larger refactoring)

The added test contains hand-edited bytecode, so there's no accompanying .as file.

[Toad06]

This will close #6204.

I also noticed a few regressions on files that are already known to have issues:

Powerpuff Girls: Attack of the Puppybots

• When the level starts, the characters and enemies no longer appear.
• Original issue: [Attack of the Puppybots] Laser attack fired from a fixed location #5277

Zelda Lampshade

• When entering the dungeon, multiple instances of the boss are now created, as well as the music. Collisions also no longer work.
• Original issue: Zelda Lampshade - Plug doesn't always pull #1989

Maybe that these cases are just a side effect and would require this to be mutable?

[moulins]

Hmm, it's interesting that both of the original issues are caused by #1513. I should try merging #5492 on top of this to see if it fixes these games.

[Herschel]

Thank you!