r300g: decouple vertex stream setup (PSC) and VS output mapping (VAP_OUT)

r300g: decouple vertex stream setup (PSC) and VS output mapping (VAP_OUT)

Formerly known as vertex_format_state. These two are completely
unrelated when using HWTCL and decoupling them makes the design
less SWTCL-centric.

When bypass_vs_clip_and_viewport gets removed, the PSC setup will
no longer be a derived state.

This change shouldn't make unbreaking SWTCL harder.