Implement complete language parser for kql

[weikanglim]

Currently, in parse.go, the parser that is used to parse the Kusto declarations is incomplete. It does not validate the declaration for full syntactic correctness, and is written rather poorly (I had many mistakes with the implementation, and cleaned it up to a semi-maintainable state). Ideally, a full language parser should be available with ksd build to avoid any authoring errors to be discovered at deployment time.

There is a .NET (and repackaged JS) parser available via https://github.com/microsoft/Kusto-Query-Language. We'd probably need to rewrite parse.go to take advantage of this, although I'm not happy with the final implementation being another language and runtime, with the needing to do interop. A different solution could be simply build an invocable program and leverage the parser that way.

We'll probably need to do some early benchmarking to ensure whichever solution we adopt, the performance isn't too terrible, and is worth the work.