Provide a functional default implementation of register in Endpoints

[PSchmiedmayer]

Provide a functional default implementation of register(to routes: RoutesBuilder) for an Endpoint to enable Corvus Users to write composable Endpoints without the need to write a register(to routes: RoutesBuilder) function

Context
Example:

/// The `Endpoint` that handles all the API interaction with `Transactions`
final class TransactionsEndpoint: Endpoint {
    var content: Endpoint {
        CRUD<Transaction>("transactions")
    }
}

would require the developer to implement the register function with a default behavior that would be applicable to all Endpoints.