anv: add shader-hash debug option

Emits a dummy MI_STORE_DATA_IMM with the shader hash in front of :
   - 3DSTATE_VS
   - 3DSTATE_HS
   - 3DSTATE_DS
   - 3DSTATE_HS
   - 3DSTATE_PS
   - COMPUTE_WALKER / GPGPU_WALKER

Example :

0x00000000:  0x10000002:  MI_STORE_DATA_IMM
0x00000000:  0x10000002 : Dword 0
    DWord Length: 2
    Force Write Completion Check : false
    Store Qword: 0
    Use Global GTT: false
0x00000004:  0xffffe0c0 : Dword 1
    Core Mode Enable: 0
0x00000008:  0x0000effe : Dword 2
    Address: 0xeffeffffe0c0
0x0000000c:  0x126e815a : Dword 3  <------------ shader hash
0x00000010:  0x78100007 : Dword 4
    Immediate Data: 309231962
0x00000000:  0x78100007:  3DSTATE_VS
0x00000000:  0x78100007 : Dword 0
    DWord Length: 7
0x00000004:  0x00000000 : Dword 1
0x00000008:  0x00000000 : Dword 2
    Kernel Start Pointer: 0x00000000
0x0000000c:  0x00040000 : Dword 3
    Software Exception Enable: false
    Accesses UAV: false

It'll correlate with the value emitted in the pipeline stats from fossil replay :

  $ grep -i 126e815a /tmp/stats.csv
  fossilize.aab93c5c3f965151.1.foz,GRAPHICS,de1b925dec8a8083,507378,498283,303434,vertex,8,50,4,0,1826,0,0,0,8,17,0,0x00000000126e815a,15

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34332>

docs/envvars.rst

@@ -878,6 +878,10 @@ Anvil(ANV) driver environment variables
     Enables video decoding support
   ``video-encode``
     Enables video encoding support
+  ``shader-hash``
+    Emits dummy (MI_STORE_DATA_IMM) instructions containing the shader
+    source hash, preceding shader programming instructions (internal
+    shaders & ray-tracing shaders are omitted)
 
    If defined to ``1`` or ``true``, this will prevent usage of self
    modifying command buffers to implement ``vkCmdExecuteCommands``. As