Add getIDL method to Service class

[dansteren]

In order to use Services in params and return types we need to implement this function.

Once this is completed, update the service example and get it passing in CI/CD.

[dansteren]

Helpful notes:

All services will have an _azleCanisterMethods on them, that is what we look for from the Rust side in order to create their rust wrapper functions. We shouldn't use that. BUT, we should likely make a separate _azleCandidMap property that stores the IDLs. So, we could have the @query and @update methods add to that map and then pull from there in the getIDL implementation on Service.

class SomeService extends Service {
    @query([text], Opt(bool))
    query1: () => boolean;

    @update([], text)
    update1: () => string;

    _azleCanisterMethods: {
        queries: []
        updates: []
    }

    _azleCandidMap: {
        query1: {
            paramTypes: [text],
            returnType: Opt(bool)

        }
    }
}