Add setaeskey and decryptaes functions

New functions:
* setaeskey: Read text file and inject key with aes policies
* decryptaes: Use a aes key stored in the SE to decrypt a given input file

Limitations:
* The decryption can only handle input files smaller or equal 512 bytes
* The decryptaes function can not handle salted input files
* The address issue is still present (see previous commit)

The example is only intended to show the se05x API usage and has multiple
security issues. Therefore, do not use this example in productive cases.