🧹 Restructure how the planner and optimizer are called

[joocer]

Planner mostly rewritten and working for basic queries. Some functions currently don't work; such as subqueries and explain

[joocer]

Problem with passing context (dates, params) should be resolved by the binder and not require the context to be handled by the subqueries.

The binder should add additional properties to the AST. This will likely need a AST visitor pattern.

[joocer]

This needs a minor refactor.

The Parser and Lexer should be called once and return an iterable of ASTs (which is kind of what it does at the moment).

These ASTs should then be executed to the end in turn:

• bind (because the execution of a query may change how the next query is bound)
• planned (because we can't plan until we're bound)
• optimize (because we can't plan until we're bound)
• execute (because the execution of query may change the outcome)

This isn't how this works at the moment.