Support Docker rootless mode & fix file ownership in root mode

[Nuru]

what && why

• Install wrapper script in $HOME/.local/bin (per XDG recommendation) if /usr/local/bin is not writable. Supports preferred solution for Files Written to Mounted Linux Home Directory Owned by Root User #594, which is to have users run Docker in "rootless" mode.
• Provide option to use BindFS to map file owners on the host. Fixes Files Written to Mounted Linux Home Directory Owned by Root User #594 for users running docker daemon as root.
• Resolves Entering Bash Subshell Results in Functions in prompt.sh and Prompt Hooks Not Being Found #766
• Resolves Permissions of prompt:kube-ps1.sh causes issues with Linux operation as non-root user #767
• Downgrade the warning for Apple M1 Emulating Intel from seriously unsupported to a notice that there may be issues. Progress on Apple M1 (arm64) Support #719 in that it appears the emulator is getting better, but still insufficient progress on native M1 support.
• Minor cleanups.

notes

This release introduces a new customization:

export GEODESIC_HOST_BINDFS_ENABLED=true

When Geodesic is launched by a shell where $GEODESIC_HOST_BINDFS_ENABLED == true it will configure /localhost so that files created by root inside Geodesic will have their ownership mapped to the same user ID and group ID as on the host. This a solution for people experiencing #594 and ONLY them. If your present solution is not creating files on the host owned by root then option will likely cause new problems.

Note further that this is a workaround and not the desired solution. Our recommendation is that you resolve the underlying issue by running Docker in "rootless" mode. This is much more secure and avoids the issue causing problems in the first place.

[drmikecrowe]

By/Large, this works as expected and I'd approve this as-is.

I would suggest adding something about GEODESIC_HOST_BINDFS_ENABLED somewhere -- I had to search for how to enable this.

[aknysh]

Suggested change

	# do not require a custome Dockerfile. See:
	# do not require a custom Dockerfile. See: