Investigate if its really needed for devcontainer to use non root user

[anton-matosov]

https://docs.github.com/en/actions/sharing-automations/creating-actions/dockerfile-support-for-github-actions#user
Docker actions must be run by the default Docker user (root). Do not use the USER instruction in your Dockerfile,
because you won't be able to access the GITHUB_WORKSPACE directory. For more information, see [Store information]
(https://docs.github.com/en/actions/learn-github-actions/variables#default-environment-variables)
in variables and USER reference in the Docker documentation.

[anton-matosov]

actions/checkout#956

[anton-matosov]

According to the github documentation, USER should not be used for containers used in actions to avoid access issues. However current setup with use of UID:GID as 1001:1001 matching default ubuntu first user allows to work around this issue. However that only works as of now on the current GitHub-hosted runners and has to be baked into Dockerfile without any flexibility at runtime as noted in actions/checkout#956.

In summary:
It works now, but is a fragile setup which may degrade with runners changes and not guaranteed to work across all workstations.
Moreover, since rosdev user has passwordless sudoer access, it doesn't really provide much of additional protection