Finalize officially-supported foxy-future branch

[emersonknapp]

Description

As part of the #657 discussion, we've realized we cannot do a full backport in a stable way.

Stabilize the exact commit and modifications for the foxy-future branch.

Related Issues

#657

Completion Criteria

• A foxy-future branch exists
• It contains a version of rosbag2 closely corresponding to Spring 2021 latest development, including many performance improvements and some new features
• It builds against the released Foxy binaries
• It is built on a regular schedule automatically to ensure stability
• The ros2 bag command for this version prints a notice "You are using Rosbag2 Foxy-future. This is an advanced alternate distribution for Foxy with performance improvements." - this notice gives users confidence that they are using the right version
• The README contains details about the "foxy-future" meaning, support, and how to use it (build it from source in your workspace)

Implementation Notes / Suggestions

See completion criteria

Testing Notes / Suggestions

See completion criteria

[JWhitleyWork]

Can this branch now be bloom-release'd as rosbag2-future?

[emersonknapp]

No - there will not be a bloom release because there isn't a way to resolve the conflicts between the binary Foxy release and the branch https://github.com/ros2/rosbag2/tree/foxy-future. You use the branch by building it from source in a workspace, against the Foxy core.

Closing this out as the branch is now finalized.