Zoekt: Query syntax transpiler spike

Background

This is the spike to research if Advanced Search to Zoekt transpiler is a viable idea.

Proposal

We should:

• Figure out if it's possible to convert Advanced Search syntax into Zoekt without the user noticing any difference
• Estimate the amount of effort

A huge benefit is that we'll be able to enable Zoekt API for everyone without it being a breaking change

References

• Advanced Search Syntax: https://docs.gitlab.com/user/search/advanced_search/#syntax
• Exact Code Search Syntax: https://docs.gitlab.com/user/search/exact_code_search/#syntax