Allows codegen of generic kernal ast
Can create a kernel outside the context then generate, i.e.:
cfg = CreateKernelConfig(cpu_prepend_optimizations=[remove_empty_loops])
kernel = create_kernel(asms, config=cfg)
kernel.function_name = 'getVelocityDensity'
sfg_config = SfgConfiguration()
with SourceFileGenerator(sfg_config) as ctx:
sfg = SfgComposer(ctx)
VelocityDensityKernel = sfg.kernels.create_from_kernel(kernel)
sfg.function("getVelocityDensity")(
sfg.call(VelocityDensityKernel)
)