Fix naming conflicts with generated C# members

[bamarsha]

This PR updates the naming scheme in the generated C# to avoid conflicts with Q# identifiers. It assumes the Q# compiler reserves __ and _. anywhere in an identifier or namespace name, and _ at the end of namespace names.

C# generation also has its own list of reserved words. If these words are used, there is no error, but the name has __ appended to it to avoid a conflict:

• Data
• Deconstruct
• Info
• Run
• ItemN where N is a natural number
• The name of the enclosing operation, function, or UDT class

Any built-in member names that are defined in a generated class need to be:

1. In the reserved word list, or
2. Surrounded on both sides by __, or
3. Implemented via an explicit interface.

The protected properties in an operation class that are generated for referenced callables use this encoding:

• If the property name uses the fully-qualified name of the callable, . is replaced with __.
• Otherwise, __ is appended to the end (but not the beginning, to avoid conflicts with built-in property names like __Body__).

TODO:

• Update tests.
• Add test cases for resolved issues.
• Run an end-to-end build.
• Enable the Data test after it is removed from the compiler's reserved words.

Related issues:

• Resolves C# code generation generates invalid code when accessing UDT items named Data. #37.
• Resolves C# code generation fails for UDTs with named items called Item*. #50.
• Resolves Some valid Q# callable names produce invalid C# code #241.
• Resolves Callables with the same fully-qualified name modulo dots cannot be called together #243.
• Resolves In the generated code, local variable may shadow a field, resulting in incorrect code #247.

[bamarsha]

Also, tip for reviewers: this PR looks scarier than it is. :) The main changes are in:

• AbstractCallable.cs
• EntryPoint.fs
• Function.cs
• MemberNames.qs
• Operation.cs
• SimulationCode.fs

The rest I think should only be trivial renamings in response to these changes.

[ScottCarda-MS]

Thanks for pointing out where to find the main changes. That made reviewing much easier.