tu: Decouple program state from the pipeline

tu: Decouple program state from the pipeline

There are a couple pieces of state that we can't calculate until we know
all of the shaders:

- The actual variants to use (i.e. whether to use safe-const variants)
- Program config and VPC draw states
- Const layout, which depends on the variants
- Whether per-view viewports should be enabled

Now that these are all combined in tu_pipeline::program, move these into
a separate struct that can be referenced directly without a pipeline.
The next step is to refactor the code filling it out so that it can be
called at draw time when given just the shaders.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25276>