Moves changes from PR #2083 to foxy

[nkalupahana]

Basic Info

Info	Please fill out this column
Ticket(s) this addresses	Closes #2368
Primary OS tested on	macOS
Robotic platform tested on	N/A

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Description of contribution in a few bullet points

• Foxy branch now builds on macOS, based on fixes from PR Fix build on macOS (10.x / 11.x) #2083! Proof of build on CI: https://github.com/nkalupahana/ros2-foxy-macos/runs/2698988683?check_suite_focus=true

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For Maintainers:

• Check that any new parameters added are updated in navigation.ros.org
• Check that any significant change is added to the migration guide
• Check that any new functions have Doxygen added
• Check that any new features have test coverage
• Check that any new plugins is added to the plugins page
• If BT Node, Additionally: add to BT's XML index of nodes for groot, BT package's readme table, and BT library lists

[SteveMacenski]

I'll merge as a batch once CI passes