feat: Add optional option to define a home directory for users created with users.conf

[Nunction]

This patch aims to add the optional option to define a home directory for users created using the users.conf.
It attempts to do so in a backwards compatibly way by adding the homedir field at the end of the users.conf line, in doing so however breaks support for passwords containing :.

If not set the home directory in HOME_DIR is used, this variable was added to the Dockerfile and is also used to for the single user mode and defaults to the existing value of /tmp. Furthermore the home directory is now created if not already present.

This would allow the use of e.g. the samba homes share where each user accesses their own home directory, currently all users use /tmp as home directory.

[cfiehe]

Nice feature 👍. I hope, it will be merged soon.

[kroese]

Can you tell me a bit more about what effect setting the home directory has?

Because I have no idea about the purpose but depending on that it might be better that we set the default to /storage instead of /tmp? Because /tmp is cleared when you update the image.

[Nunction]

In the context of samba it should primarly affect how the homes share is handled, which if not explicitly set shares the home directory of the user.

The [homes] section
...
If no path was given, the path is set to the user's home directory.
-- https://www.samba.org/samba/docs/current/man-html/smb.conf.5.html

As well as affecting the value of the %H substituion which is the home directory of the user.

Regarding the default value I just reused /tmp as this is the value currently used in the entrypoint. Might be worth setting it to /storage in case the homes share is used with the default volume.