Add ability to parse check flux query AST

In script editor mode, the UI should be able to submit flux query to the parser to get AST, and compare AST to a template check flux query. We should be able to parse check parameters and allow user to switch to an alert builder mode if the AST from the custom flux query matches the template.

Start by locating the script editor entry point and the parser integration for Flux queries. Trace how the UI could receive an AST, compare it with a template check query, and extract check parameters. Done means matching custom queries can expose their parameters and enable alert-builder mode.

Written by the indexing model from the issue text.