Create CRUD triggers for raw tables

[simolus3]

This adds the powersync_create_raw_table_crud_trigger function, taking three arguments:

1. A JSON string description of the raw table.
2. The name of the trigger to create.
3. The type of write (INSERT, UPDATE or DELETE for which to generate a trigger). Typically users would create all three, but maybe they want the default trigger for some types only and customize the rest 🤷.

The function generates and executes a CREATE TRIGGER statement mirroring our suggestions from the documentation. To do this,

• The definitions of raw tables is extended to contain the same options (include_old and boolean flags like insert_only) we already have for regular tables. Also, the optional local_name field has been added to describe the name of the table in the local schema (since name in raw tables describes the sync optype to match).
• To infer column names used to generate JSON fragments, we query pragma_table_info at the time the trigger is created.

Triggers are not created automatically, and users have full control over their name. So this is a tool that users would invoke in their schema migrations if they can use the default patterns for triggers (which we assume to be the case in most scenarios).

The created trigger follows the scheme of the one we create for JSON-based views. Insert-only tables are implemented by raising on updates and deletes.
I've introduced the SchemaTable enum to wrap either a JSON-based table or a raw tables + inferred column names. This allows some methods generating JSON fragments to be reused between the two. I've also removed type arguments on SqlBuffer::insert_into_powersync_crud in favor of &dyn references to avoid monomorphization on that fairly large function.

[rkistner]

Could you add tests for the generated trigger SQL? Not sure if Dart has something like snapshot tests for this - it's fine if it changes over time, but it would be good to see the specific record of that.

Then I'm also wondering - is there a nice way to handle "local-only" columns like documented here? https://docs.powersync.com/client-sdks/advanced/raw-tables#exclude-local-only-columns-from-triggers (recently added). Otherwise we just need to be explicit that those are considered "advanced" use cases that needs manually-defined triggers.

[simolus3]

Could you add tests for the generated trigger SQL?

There aren't vitest-like automated snapshots that I'm aware of, but I've added a few hardcoded examples as matches.

Otherwise we just need to be explicit that those are considered "advanced" use cases that needs manually-defined triggers

That was what I had in mind originally, but it seems like a fairly simple pattern to handle internally. I've added the local_only_columns field for this. It generates this trigger.