a4xx: add image/buffer/compute support
This depends on MR !14789 (merged), as the encoding of the ops is slightly different between a4xx/a5xx.
A few things which could be improved:
- LDIB support for arbitrary formats (needed for desktop GL)
- Using fewer "driver" uniform locations for compute
In combination with some enablement patches (and other features), this passes most of the dEQP / KHR ES3.1 suites.