ilo: toy_compiler_disassemble() should take a ilo_dev_info

That allows it to be called anywhere, without requiring a toy_compiler.
ilo: add a builder for building BOs for submission

Comparing to how we manage batch and instruction buffers now, the new builder

 - does not flush automatically
 - manages STATE_BASE_ADDRESS
 - uploads kernels using unsynchronized mapping
 - provides many helpers
ilo: make ilo_cp based on ilo_builder

This is the first step.  We want ilo_builder in ilo_context in the end.