tu: Make tile stores use a dedicated CS

tu: Make tile stores use a dedicated CS

We were trying to calculate how much space they need, That was already
difficult and one of the most opaque and hard-to-verify uses of sub_cs,
but it will become even more difficult with the 3D path. What's worse is
that sometimes we have to touch that path when we start touching
registers that would affect rasterization, and there's no indication
that you have to then recalculate the size etc. Just rip this out and
start keeping a separate CS for it instead. Note that this adds a small
amount of memory wastage and extra buffers (at worst one buffer per
command buffer).

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12102>