Feat: App extraction/decryption

[NinjaCheetah]

The final component of being able to extract a WAD is to be able to extract each individual content from the content blob retrieved with get_content_data() from wad.py and then decrypt them into .apps. The Title Key of a given title can now be read from the ticket using ticket.py/crypto.py, and the size of all of the contents can now be retrieved from the TMD thanks to tmd.py. This means that all of the pieces exist, and now just need to be put together.