Add CompilerMSL emit_instruction() and emit_glsl_op() functions
to handle MSL-specific operation and function definitions.
Remove CompilerMSL emit_msl_defines() function.
Use entry point name if no function name provided.
When flattening in/out structs, qualify member names with struct name.
Fix issue when determining declared size of struct types.
Refactor use of m_ name prefix.
Identify header defines in MSL code.
Add Decoration qualified_alias element.
Virualize Compiler to_name() function.
MSL use qualified_alias instead of alias when inside entry-point function.
Reformats the entire codebase. Better to do it now than later.
Adds .clang-format and a convenience script format_all.sh which formats
everything automatically.
Add virtual CompilerGLSL emit_sampled_image_op function for OpSampledImage.
Under MSL, set sampler ID for local OpSampledImage objects and extract it when emitting sampler.