Support operators in CodeGenerator

[kevmal]

Addresses issue #206

Shadows (|SpecificCall|_|) in CodeGenerator to match on target methods. Otherwise https://github.com/fsprojects/FSharp.TypeProviders.SDK/blob/592d23a96db79b4248ed23a062db3a17433282ce/src/ProvidedTypes.fs#L13893-L13906 never matches.

Still some missing operators and more testing is needed (particularly for unsigned ints).

Certain operators don't have a NoDynamicInvocation such as (+) and (*) but are still included here. Ops so far:

~-
~+
-
+
*
/
% 
|||
^^^
~~~
&&&
int32/int
float/double
float32/single
int16
int64
byte
sbyte
uint32
uint16
uint64

@dsyme Any general feedback on this before continuing?

[dsyme]

The general direction is looking good

See also https://github.com/fsharp/fslang-design/blob/master/RFCs/FS-1071-witness-passing-quotations.md which would mean we don't have to do this thing, as FSharp.Core would have callable entrypoints for all operators.

[dsyme]

@kevmal This looks ready to go?

[kevmal]

This should be good for now.

Some of what's not included here:

• hash/ compare/ pown though they should still work through FSharp.Core calls.
• Operators.Checked -- could still get exceptions from some of these
• isNull -- I may need to handle this at some point (works fine)
• reraise -- This will not work and will need to be supported at some point

Included the System.Math ops which could also moved out of CodeGenerator since most don't emit specific IL.

[dsyme]

Thank you!!