Add pattern and magic for more Arma 3 files

[MrClock8163]

Grouped Arma 3 format patterns into their own folder

Adds:

• pattern file and magic for the texHeaders.bin texture index file used in Arma 3 PBO archives
• pattern file and magic for MLOD type P3D model files
• pattern file and magic for rapified configuration files

Small improvements to the PAA pattern:

• Data description
• Better indication of internally compressed mipmaps

[MrClock8163]

Sorry for the rapid fire PRs by the way.
I had these patterns for a few years now. I'm just cleaning them up.
I have one or two more formats to submit later.

[WerWolv]

Thank you! No problem
If you're planning on adding more Arma related patterns, could you move them all into a subdirectory? We have some patterns like that for a final fantasy game already too that had multiple files so it would make sense to structure your files similarly

[MrClock8163]

Yeah, sure I can.
I definitely have one more (the P3D model format), and maybe one more (binary config).

Do you want me to move them in this PR?
When I move them, do you want me to make them a single entry in the README as well, or leave them one by one?

[WerWolv]

Feel free yeah. I can also leave this PR open until you add your remaining files

[MrClock8163]

As requested, I moved the Arma 3 patterns into an a3 subdirectory.
For the time being, this is all the formats I have patterns for.

[MrClock8163]

@WerWolv Could you review the additions and possibly merge them, if everything is up to spec?

[WerWolv]

Merged! Sorry for the delay

[MrClock8163]

Thank you!