Iron Irwini support

[ted-miller]

• Add project infrastructure
• Remove remap rules
• Update documentation

[gavanderhoorn]

Honestly, I'm hesitant to approve this as it basically breaks existing functionality.

I agree with your comment that we should support Iron already, but remaps do see use.

I'm not sure whether having Iron supported without remapping is a good idea.

But I won't block it if you really want to merge it in.

(I would recommend rebasing though, instead of merging in main)

[ted-miller]

This passes all my testing.

[ted-miller]

Since Iron Irwini is EOL in a month, we will skip this release and focus on Jazzy, which is LTS.

[ted-miller]

NOTE: The work in iron_wip will be carried forward into the jazzy release

[gavanderhoorn]

@jimmy-mcelwain @ted-miller: the strtoll(..) implementation -- if really needed -- should ideally go into the posix shim. Not in MotoROS2 itself.