shader: emulate DS_ORDERED_COUNT as a GDS atomic (#1117)

* feat(shader): emulate DS_ORDERED_COUNT as a GDS atomic

* fix(shader): issue one ordered-count atomic per wave

* shader: correct ordered-count addressing and wave results

Use the M0 base and pixel packer offset for the GDS counter. Broadcast the
previous value to every lane and preserve the counter when EXEC is empty.

Add GPU regressions for add/exchange with full, partial, and empty EXEC in
wave32 and wave64. The targeted DS and buffer atomic suite passes 63 cases.

---------

Co-authored-by: nmzik <Nmzik@mail.ru>

src/graphics/shader/recompiler/frontend/decode/ShaderDecoder.h

@@ -580,6 +580,7 @@ enum class Opcode {
 	DS_BPERMUTE_B32,
 	DS_CONSUME,
 	DS_APPEND,
+	DS_ORDERED_COUNT,
 	DS_READ_I8,
 	DS_READ_U8,
 	DS_READ_I16,