[GodMode] Expression to IL intrinsic

[dadhi]

Thinking about #234 expression relative complexity, and as we are controlling the IL emit, we can as well provide the hook for the User to emit the IL for the specific expression.

For instance, given MethodCallExpession for specific method info and the user-provided IL emitter for this method body, we can use provided IL directly instead of generic FEC expression visitor and emitter.

FEC may also provide its own recognizable for such inlining "intrinsic" methods, e.g. call to:

T TryOrDefault<T>(Func<T> func, List<Exception> errors) 
{
   try { return func(); }
   catch(Exception ex) { errors.Add(ex); return default; }
}

maybe replaced with the method code and func expression Body avoiding the separate nested lambda compilation.

[dadhi]

We may as well write to the m_ILStream directly.
For instance, we may have an interface method with (byte[] ilStream, ref int ilLength, Stack stack) so the expression implementing this interface may call and output codes/bytes directly to stream.

[dadhi]

Currently trying with DryIoc a more direct approach: https://github.com/dadhi/DryIoc/tree/fec-intrinsics

Adding to the LightExpression.Expression a set of hooks:

        public virtual bool IsIntrinsic => false;

        public virtual bool TryCollectBoundConstants(CompilerFlags config, ref ClosureInfo closure, IParameterProvider paramExprs, 
            bool isNestedLambda, ref ClosureInfo rootClosure) => false;

        public virtual bool TryEmit(CompilerFlags config, ref ClosureInfo closure, IParameterProvider paramExprs, 
            ILGenerator il, ParentFlags parent, int byRefIndex = -1) => false;

And making public the parts of the ExpressionCompiler and the ExpressionVisitor which can be used when overriding the methods in the Expression.

Let's see how it goes...

[dadhi]

works pretty well

[dadhi]

Here is how much difference does a single ConvertViaCastClassIntrinsic:

Intel Core i5-8350U CPU 1.70GHz (Kaby Lake R), 1 CPU, 8 logical and 4 physical cores
.NET Core SDK=6.0.102
[Host]     : .NET Core 6.0.2 (CoreCLR 6.0.222.6406, CoreFX 6.0.222.6406), X64 RyuJIT
DefaultJob : .NET Core 6.0.2 (CoreCLR 6.0.222.6406, CoreFX 6.0.222.6406), X64 RyuJIT

|                                               Method |      Mean |     Error |    StdDev | Ratio | RatioSD |  Gen 0 |  Gen 1 |  Gen 2 | Allocated |
|----------------------------------------------------- |----------:|----------:|----------:|------:|--------:|-------:|-------:|-------:|----------:|
|                CreateLightExpression_and_CompileFast | 12.954 us | 0.2578 us | 0.3859 us |  1.00 |    0.00 | 1.8005 | 0.8850 | 0.0610 |    5.6 KB |
| CreateLightExpression_and_CompileFast_with_intrinsic |  8.033 us | 0.1321 us | 0.1764 us |  0.62 |    0.02 | 0.8698 | 0.4272 | 0.0458 |   2.67 KB |