pan/bi: Rename panfrost/bifrost -> panfrost/compiler

This is the compiler for both Bifrost and Valhall, and presumably future
Mali GPUs too. Give it a more generic name so we can use the bifrost/ path for
something a bit more specific.

For historical reasons the compiler's name is still "bifrost" and uses the
prefix `bi_`. I think that's ok in the same way that i915 in the kernel supports
way more than just i915.

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20455>

.gitlab-ci/test-source-dep.yml

@@ -311,7 +311,7 @@
       - src/panfrost/vulkan/*
       when: on_success
     - changes:
-      - src/panfrost/bifrost/**/*
+      - src/panfrost/compiler/**/*
       when: on_success
 
 .broadcom-common-rules: