Address issues with GLSL style global in/out vars (#6669) (#6998)

* Address issues with GLSL style global in/out vars (#6669)

Asserts and segfaults were observed trying to compile a simple
vertex shader like:

````
in int2 inPos;

[shader("vertex")]
main(uniform int2 test1, int2 test2, out float4 pos: SV_Position)
void main()
{
    // Bogus use of all input vars to prevent optimizing out.
    pos = float4(inPos.x, test1.x, test2.y, 0);
}
````

Further investigation found that while replacing "uniform int2 test1"
with "int2 test1" allowed for successful compilation, the resulting
output shader would have overlapping location qualifiers. For example,
compiling the above with "int2 test1" to glsl might give:

````
...
layout(location = 0) in ivec2 test1_0;
layout(location = 1) in ivec2 test2_0;
layout(location = 0) in ivec2 translatedGlobalParams_inPos_0;
...
````

This was because Slang does not actually support mixing GLSL style global
in/out vars and entry point params. However, this is never checked for
or noted in documentation. Slang source also assumes input shaders do not
mix these and these assumptions ultimately led to the observed asserts
and seg faults when using uniform entry point params.

This change makes updates to throw an error when the compiler detects that
it is trying to translate global in/out variables into entry point params
when an entry point already contains parameters, allowing for compilation
to fail gracefully.

Certain tests have been updated to avoid mixing GLSL style global in/out
vars and entry point params. This was mostly for tests that were using
functions like WaveGetLaneIndex which use global in vars for certain
platforms (see __builtinWaveLaneIndex).

* Address issues with GLSL style global in/out vars - updates 1 (#6669)

Update addresses review feedback to support mixing GLSL-flavored global
in/out vars and entrypoint parameters when either all global in/out vars
or all entry point params have a system value binding semantic.

* Address issues with GLSL style global in/out vars - updates 2 (#6669)

This update attempts to actually allow mixing GLSL style global in
vars and entry point vars.

Change attempts to recalculate offsets when adding the global input
vars into the recreated entry point params layout.

Additional updates were made to:

-resolve further issues uncovered with entry point uniform params.

-Address improper use of SV_DispatchThreadID in wave-get-lane-index.slang
 for metal. "thread_position_in_grid" is not supported for signed integer
 scalars or vectors.

-Fix a spirv casting conflict due to the implementation of
 gl_PrimitiveID.get conflicting with PrimitiveIndex().

-Add a call to remove a global var in replaceUsesOfGlobalVar(). The global
 var is already replaced in this function and keeping it around can prevent
 it from being cleaned up by DCE if it still has decorations.

* format code

---------

Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>

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