ENI Hotplug / udhcpc script
* works with all Alpine versions back to 3.9
* udhcpc handles ENI's primary IPv4
* post-bound/post-renews eth-eni-hook handles secondary IPv4 & IPv6 addresses, route tables, and rules
setup-ami tweaks
* move scripts to be installed into setup-ami.d/
* move config snippets into setup-ami.d/etc/ (previously embedded in setup-ami)
Profiles can specify 'setup_script' to do additional things. If additional files/dirs are required, a 'setup_copy' map will copy them to the build instance so that 'setup_script' can use/install them.
TBD: docs.
There is an increasing need to share components among the various
commands, especially with the introduction of the identity broker API.
Rather than trying to assemble an importable python library of code for
the build process I think we can just combine everything into one file
and use argparse sub-commands to integrate them into a set of
individually callable scripts. This change does that integration.
