feat: add retina-shell image for Linux

[wedaly]

Description

Build a new image retina-shell for adhoc network debugging on Linux nodes/pods.

Related Issue

#910

Checklist

• I have read the contributing documentation.
• I signed and signed-off the commits (git commit -S -s ...). See this documentation on signing commits.
• I have correctly attributed the author(s) of the code.
• I have tested the changes locally.
• I have followed the project's style guidelines.
• I have updated the documentation, if necessary.
• I have added tests, if applicable.

Screenshots (if applicable) or Testing Completed

Tested building with the following commands:

IMAGE_REGISTRY=widalytest.azurecr.io BUILDX_ACTION=--push PLATFORM=linux/amd64 make retina-shell-image
IMAGE_REGISTRY=widalytest.azurecr.io BUILDX_ACTION=--push PLATFORM=linux/arm64 make retina-shell-image
IMAGE_REGISTRY=widalytest.azurecr.io BUILDX_ACTION=--push make manifest-shell-image

Then ran it locally:

Additional Notes

There are two issues with the AzLinux 3 base image that should be fixed in the upcoming AzLinux3 release. See comments in the Dockerfile for details.

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