Filament uses a handful of known UBO, the code for creating their
interface block is not needed in filament (via filabridge), so
reorganize things so that we can move that code to filamat.
On the other hand, filament needs the C structure corresponding to
the UBO, to find the fields offset and ubo size and name.
We now have a UibStructs.h in filabridge which only defines C struct
with a static name for the interface block's.
This should slightly reduce the size of filament proper.
We also now have a new helper TypedUniformBuffer<> which simply holds
one of these structs (or an array), and allows to set the fields
directly and more naturally from C++. std140 alignment is now left to
the caller, when going through that class.
ba10393f48