Decryption and decompression fixes and changes

[CosmicDreamsOfCode]

• Move shared decryption code into a new method to clean up a bit
• Change decryption of assets to decrypt pages for compressed assets, this fixes assets with more than 1 compressed page failing to decrypt properly
• Fix an issue where assets with 1 compressed page would fail to decompress because the output buffer wasn't correctly sized
• Fix camel data is zlib compressed #5 by checking for the toc compression method when decompressing non-oodle assets
• Fix localised assets and and part E slices still attempting to get data even if the sdfdata doesn't exist, return null for the former
• Change exposed Assets enumerable to a list of file names instead, this is more compatible with the methods we have in GameManager for getting asset data, also added a a method to get this list through the GameManager, as it was previously inaccessible

[wannkunstbeikor]

just some small changes and one question, but looks good