Decompiling constants of the target type

[sharwell]

Originally reported by @davkean in dotnet/roslyn#25006:

The following:

        internal int ActualMaxDegreeOfParallelism
        {
            get { return (_maxDegreeOfParallelism == Unbounded) ? int.MaxValue : _maxDegreeOfParallelism; }
        }

gets decompiled to:

		internal int ActualMaxDegreeOfParallelism
		{
			get
			{
				if (this.m_maxDegreeOfParallelism != -1)
				{
					return this.m_maxDegreeOfParallelism;
				}
				return 2147483647;
			}
		}

Similar to other decompilers, we should be smarter around replacing magic "literals" with their appropriate constants.

I suggest implementing the feature mentioned by @CyrusNajmabadi in dotnet/roslyn#25006 (comment):

... looks in the Type for that value for any constants matching the value. If it finds any, it will use them. As such, it will replace constants with things like int.MaxValue, double.Infinity, ...

🔗 This is related to #517, but is much more narrowly-scoped and (I believe) much easier to implement as an interim solution covering majority cases.

[siegfriedpammer]

@sharwell @davkean Would you expect the decompiler to replace literals with constants everywhere? Even in constant / enum declarations?

Which one do you prefer? enum E : sbyte { A = 0x7F } or enum E : sbyte { A = sbyte.MaxValue }

(Of course the definition of public const double NaN in System.Double and others would not reference itself.)