Add 3 GameAudio::Main methods implementation

[joakim-d]

• Implement GameAudio::Main::bootDSP
• Implement GameAudio::Main::isActive
• Implement GameAudio::Main::isWaveLoaded

[cristian64]

I've checked that the three implementations show 100% in objdiff.

[SwareJonge]

Thanks for your first contribution! There are a few things i'd like being addressed and that's mainly that i'd rather have PRs per file/TU now that this project still has many files that have no work done to it(So this will change in the future).
For now i will accept it but also be aware that many implementations of structs are also unfinished so in GameAudio::Main::isActive you wrote return _48[0] & 0x10;
_48 is currently an array in the structure for padding reasons, so that should be an individual member.
So the written code would be return _48 & 0x10; or perhaps rename _48 which you think make sense by observing what it does/affects.

Most of these issues are also kinda on me for not having a contributors guide so my apologies.

[decomp-dev]

Report for MarioClub_us (8a91a6b - 96e2dc3)

📈 Matched code: 45.72% (+0.01%, +168 bytes)

✅ 3 new matches

Unit	Item	Bytes	Before	After
main/Inagaki/GameAudioMain	GameAudio::Main::isWaveLoaded(GameAudio::Main::WS_ID)	+120	3.23%	100.00%
main/Inagaki/GameAudioMain	GameAudio::Main::bootDSP()	+28	12.50%	100.00%
main/Inagaki/GameAudioMain	GameAudio::Main::isActive()	+9	33.33%	100.00%

📉 1 regression in an unmatched item

Unit	Item	Bytes	Before	After
main/Inagaki/GameAudioMain	.sbss	-18	70.59%	26.67%

[joakim-d]

Hello and thanks for taking the time to review my PR.
Indeed I had no idea that a whole file/TU was preferred.
I'll try to focus on a whole class now!

I hope my latest changes will match with what you expected.
I changed the name to mState as it looks like this variable tracks some kind of object state.
I think it is used in resetAudio and some other methods.