Support falling through with associated data

- introduce Response::FallThrough(std::string) as an overload
- add fallthrough_data as a member of dispatchable and require it
    in constructor;
- support pass_associated_data in protocol_config.json
- if the latter is specified, pass additional parameter to impl method.

Bug: 512156136
Change-Id: I64ddf774c27e116092535c431c9ec71b7dec7b91
6 files changed