Implement Vfpu instructions

[soywiz]

A first step would be to get cubevfpu demo running, and later vfpu tests from pspautotests.
Initially in interpreted mode.
Once it is implemented right, we can backport the implementation to dynarek.

[soywiz]

Reference implementation: https://github.com/jspspemu/jspspemu/blob/d9c3ebf40a91abfd891becd703f6e832e082f07c/source/src/core/cpu/cpu_codegen.ts#L465