asahi,agx: Use new tilebuffer infrastructure

Flag day change to replace the previous hardcoded background/end-of-tile shaders
and the API-style load/store_output in fragment shaders with the generated
shaders and lowered *_agx intrinsics. This gets us working non-UNORM8 render
targets and working MRT. It's also a step in the direction of working MSAA but
that needs a lot more work, since the multisampling programming model on AGX is
quite different from any of the APIs (including Metal).

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19871>

src/asahi/compiler/agx_compiler.h

@@ -300,15 +300,18 @@ typedef struct {
       uint32_t component;
       uint32_t channels;
       uint32_t bfi_mask;
+      uint16_t pixel_offset;
       enum agx_sr sr;
       enum agx_icond icond;
       enum agx_fcond fcond;
-      enum agx_format format;
       enum agx_round round;
       enum agx_lod_mode lod_mode;
       struct agx_block *target;
    };
 
+   /* For local access */
+   enum agx_format format;
+
    /* For load varying */
    bool perspective : 1;