vkd3d-shader/fx: Implement writing fx_2_0 object initializer data sections.

Object data is used for strings, textures, and shaders. Samplers are handled separately.
The section is a contigious stream of <id><size><object-data>, size field is used
to advance to the next <id> position.

Signed-off-by: Nikolay Sivov <nsivov@codeweavers.com>

tests/hlsl/effect-annotations-fx_2.shader_test

@@ -64,9 +64,12 @@ float4 main() : sv_target
 
 technique {}
 
-[effect todo]
+[effect]
 technique < string a = "test"; > {}
 
+[effect]
+technique < string a = ""; > {}
+
 [effect fail]
 // Without closing semicolon
 technique t1 < int a = 1 > {}