Add type unification logic to handle LambdaDecl/Functor's with FuncType

[16-Bit-Dog]

Issue:

• Partially addresses Implicit casts not always considered for generic value deduction from passed-in function signatures #9003
  • fixes the case of foo2

Problem & Soluition:

• Currently, generic inference fails if using lambda as argument to a function-type parameter since Slang does not handle this case during type unification. This missing logic was added.
  • inferGenericArguments->tryUnifyTypes->TryUnifyFuncTypesByStructuralMatch

[jkwak-work]

Looks good to me

[jkwak-work]

Looks good to me

[16-Bit-Dog]

I think this PR may be missing logic to handle inference for Functor's (as argument, not only lambda's).

PR will be made a draft until I figure out if this is missing or not.

Example:

//TEST:COMPARE_COMPUTE(filecheck-buffer=CHECK):-vk -output-using-type
//TEST:COMPARE_COMPUTE(filecheck-buffer=CHECK):-cpu -output-using-type

//TEST_INPUT: set outputBuffer = out ubuffer(data=[0 0 0 0], stride=4)
RWStructuredBuffer<int> outputBuffer;

// This test ensures that lambdas correctly unify-types with function-types so that
// generic-parameters can be infered.
func foo<let N : int>(f: functype()->vector<float, N>)->vector<float, N> { return f(); }

struct Functor : IFunc<vector<float, 1>>
{
    vector<float, 1> operator()()
    {
        return 4.0;
    }
}

[numthreads(1,1,1)]
func computeMain()->void
{
    //CHECK: 2
    // outputBuffer[0] = (int)foo(() => 2);
    //CHECK: 3
    // outputBuffer[1] = (int)foo(() => vector<float, 1>(3));

    //CHECK: 4
    Functor f;
    outputBuffer[2] = (int)foo(f);
}

[16-Bit-Dog]

Update: generalized the current approach to support Functors

[jkwak-work]

Looks good to me