[abigen][banjo] Support syscall-ktrace-info.inc generation from banjo

Add a new banjo backend for the various kernel generation types, and
also have it support generating its first subtype. The output of this
backend is identical to the current generated file from abigen, except
for the copyright block at the top of the file.

ZX-3882 #comment [abigen][banjo] Support syscall-ktrace-info.inc generation from banjo

Test: new codegen_tests
Change-Id: Ib229cc73b69dd52555451291317e559ed7f78738