Allowing catch to work with any request types

[matt2e]

Currently when declaring a retry with a catch, the catch verb must include the exact request type. eg:

//ftl:verb
//ftl:retry 1 1s catch catchExample
func Example(ctx context.Context, req ExampleRequest) error {...}

//ftl:verb
func CatchExample(ctx context.Context, req builtin.CatchRequest[ExampleRequest]) error {...}

This prevents these use cases:

• Defining a single catch verb that can be used for multiple retryable verbs (assuming they don't have the exact some request type)
• Defining a catch in FSM's retry directive, as each transition has different event types

It could be useful to have a catch verb with takes builtin.CatchRequest[map[string]Any] or just builtin.CatchRequest[Any].

Something to be careful about:

• A failing catch verb currently retries forever
• If a request can't be unmarshalled into the request type at runtime we could easily end up repeatedly failing forever...

[alecthomas]

I think allowing Any makes sense.

[matt2e]

decision: Allow Any or exact match, add request type ref