Exposes OpControlBarrier and OpMemoryBarrier so compute kernels do not
need to hand-roll inline asm for workgroup synchronisation. Scope and
MemorySemantics mirror the SPIRV-Headers unified1 grammar bit-for-bit;
workgroupBarrier() matches the semantics of GLSL barrier().
Co-authored-by: Quint Daenen <quint@daenen.email>