Added remote authentication environment variables

[mattycourtney]

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• I have read the contributing guideline and understand that I have made the correct modifications

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Description:

Added environment variables to control NetBox's remote authentication configuration parameters

Benefits of this PR and context:

This PR enables users of the container image to control NetBox's remote authentication configuration parameters using environment variables.

Configuring remote authentication facilitates SSO via reverse proxy servers that add a HTTP header to indicate the authenticated user's identity.

How Has This Been Tested?

• Tested the change with the the Jenkins Builder (running locally) and confirmed that the generated README.md file was correct
• Deployed a container with none of the REMOTE_AUTH_* environment variables set, and validated that the generated configuration.py file was as expected
• Deployed a container with REMOTE_AUTH_* environment variables set, and validated that the values were present in the configuration.py file

Source / References:

• https://netbox.readthedocs.io/en/stable/configuration/optional-settings/#remote_auth_enabled
• https://netbox.readthedocs.io/en/stable/configuration/optional-settings/#remote_auth_backend
• https://netbox.readthedocs.io/en/stable/configuration/optional-settings/#remote_auth_header
• https://netbox.readthedocs.io/en/stable/configuration/optional-settings/#remote_auth_auto_create_user
• https://netbox.readthedocs.io/en/stable/configuration/optional-settings/#remote_auth_default_groups
• https://netbox.readthedocs.io/en/stable/configuration/optional-settings/#remote_auth_default_permissions

[LinuxServer-CI]

I am a bot, here are the test results for this PR:
https://ci-tests.linuxserver.io/lspipepr/netbox/v2.10.4-pkg-0a2c9289-pr-13/index.html
https://ci-tests.linuxserver.io/lspipepr/netbox/v2.10.4-pkg-0a2c9289-pr-13/shellcheck-result.xml

[mattycourtney]

I'm really keen to see this get merged, as I use REMOTE_AUTH to SSO to Netbox hosted behind an identity aware proxy. Please let me know if there's any more detail I can provide within this PR that will aid your evaluation.

[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[mattycourtney]

bump

[LinuxServer-CI]

I am a bot, here are the test results for this PR:
https://ci-tests.linuxserver.io/lspipepr/netbox/v2.10.6-pkg-4cdd4aed-pr-13/index.html
https://ci-tests.linuxserver.io/lspipepr/netbox/v2.10.6-pkg-4cdd4aed-pr-13/shellcheck-result.xml

[alex-phillips]

LGTM