feat(web-analytics): Change query runner query type

[robbie-c]

Problem

I wanted the query runner to use the Node type in python as part of #17629

Changes

• Change the schema.ts -> json -> py so that it exports everything in the file.
• This meant that I needed to move some types into a different file if they were not convertable. Specifically, I moved QueryContext and QueryContextColumn, as they are not needed outside the front end and include a function type.
• Change the QueryRunner to use the Node type
• Changed any python references from schema.Model to schema.QuerySchema, because the root model is no longer useful.

How did you test this code?

Relied on the CI suite

[posthog-bot]

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