Modify implementations to use one Participant per Context

[ivanpauno]

Feature request

Feature description

Design document here.
The idea is to implement everything in the rmw layer, and avoid changes in upstream layers as much as possible.

Tasks already done:

• Port rmw_fastrtps.
• Create common package rmw_dds_common, to allow easiest porting of remaining rmw implementations.
• Disable failing cross vendor tests (@ivanpauno)
• (security) Update sros2 and test_security.

To do:

• Migrate rmw_connext (not needed, we changed to rmw_connextdds which is one-participant-per-context)
• Migrate rmw_cyclonedds

[ivanpauno]

@hidmic @dirk-thomas @wjwwood FYI

[ivanpauno]

Linked PRs:
rmw_fastrtps: ros2/rmw_fastrtps#312
rmw: #189
rmw_implementation: ros2/rmw_implementation#77
rcl: ros2/rcl#515
rmw_dds_common (new package): ros2/rmw_dds_common#4
rmw_cyclonedds API update: ros2/rmw_cyclonedds#106
rmw_connext API update: ros2/rmw_connext#392

[ivanpauno]

I've updated the ticket with more up to date information.

[clalancette]

I'm fairly sure this is done now. At least, I know for sure that it is fixed in Fast-DDS and Connext. I'm also fairly certain this is the case for Cyclone DDS. @eboasson @ivanpauno Please feel free to reopen if I'm wrong about Cyclone.