Rust graphql parser

[kindermax]

PoC - reimplement graphql query parsing in rust.

Comparing:

• python parsing with graphql-core (original)
• rust parsing + converting rust ast into graphql-core ast - (so we do not need to rewrite core which works with graphql-core ast)
• rust parsing but w/o converting rust ast into py ast (using mocked py ast for simple query)
• just mocked py ast (no parsing at all)

Comparing these four situations allows to see what part of flow is actually slow.

Here we see that rust_real vs rust_mock shows that parsing and converting rust ast into graphql ast almost 2x slower than just parsing rust ast and return mocked graphql ast (skipping AstConverter part)

The goal is to show if rust parser is suitable in this case.

[kindermax]

As an alternative, a simple lru-based ast cache was added. If queries do not change too often and do not use inline variables, ast cache must to be very efficient.