Add type hash to rmw_topic_endpoint_info_t (rep2011)

[emersonknapp]

Part of ros2/ros2#1159 Depends on ros2/rosidl#722

Adds topic_type_hash field to rmw_topic_endpoint_info_t so that it can be filled by RMW implementations.

[emersonknapp]

@wjwwood @methylDragon @ivanpauno this is ready for review, the types are finalized in the dependency PR, we're only hashing out final details

[clalancette]

Now that https://github.com/ros2/rosidl/pull/722 is merged, we can run CI on this one alone and merge it in:

CI:

• Linux
• Linux-aarch64
• Windows

[clalancette]

I had to rebase this to get the incompatible type stuff in. I've done that now, here is another CI:

• Linux
• Linux-aarch64
• Windows

[clalancette]

The test failures on Windows are known flakes. So going ahead and merging this one in.