add support for gzip compressed user data to early-boot-config

[bcressey]

What I'd like:
early-boot-config should support gzip compressed user data, in addition to uncompressed TOML.

With #1244 and #1317 we could get enough input that we'd otherwise run into the 16 KiB limit for EC2 instance user data. Compression will make this channel more useful.

Any alternatives you've considered:
Continue to accept plain text only. This would require people to switch to host containers or post-boot configuration mechanisms such as SSM workflows for more scenarios, which is relatively more difficult to coordinate.