vkd3d-shader/tpf: Compile HLSL to tpf through vsir, part 2.

As a reminder, the idea is to translate all the hlsl_ir_node instructions to a vsir_instruction in a vsir_program, so that tpf_compile no longer needs hlsl_ir constructs such as a hlsl_ir_function_decl.

Until all the nodes are translated, the hlsl_ir_function_decl.body block will still be in charge of determining the instruction order, so, like for the hlsl->vsir->d3dbc translation, the hlsl_ir_vsir_instruction_ref instruction type is introduced as a temporary way to have an hlsl_ir instruction refer to a vsir_instruction.

Since hull and domain shader support, currently being introduced by @shaunren, require access to both the entry_func and the ctx->patch_constant_func there are now two hlsl_ir_blocks that will have hlsl_ir_vsir_instruction_ref pointing to the instructions added to the vsir_program. Eventually the vsir_program will merge the instructions for both these blocks and add the right markers such as HS_FORK_PHASE.

In this series I write the DCL_TEMP_COUNT and DCL_INDEXABLE_TEMP as vsir instructions and move the temp allocation back to hlsl_codegen.c, which I think is required to complete the hlsl->vsir->tpf translation, since allocation should be solved for a well formed vsir_program.

PD: I will focus on translating hlsl_ir_node instructions not related to hull and domain shaders now to avoid conflicts.