Gets rid of some indirect inclusions in cpp files.
Also this will reduce the amount of rebuilt files if
changes occur in the DataReader header.

Also remedies places where the video backends and core rely on things
being indirectly included.

Suggested by degasus.

Move ownership of cached_arraybases from CPMemory to VertexLoaderManager
to better match it usage.

Yet another story of games loading weird shit into registers.

For some reason, Burnout 2 would (in rare situations) load invalid
addresses into cp_state.array_bases. What would the real hardware
do in this situation? Who knows, Burnout 2 doesn't actually enable
the vertex array with the invalid address so nothing kinky happens.

But dolphin tries to optimise things and starts using the address
as soon as it is loaded into memory. This causes GetPointer (which is
now much more vocal) to throw an error.

The Fix:  We don't call GetPointer until we are sure the vertex array
has been enabled.