Distribute webmin module code with netatalk proper

[rdmark]

A webmin module (administrative webapp for netatalk) is currently maintained in a separate repo at https://github.com/Netatalk/netatalk-webmin/tree/main

This is to discuss potentially folding this codebase into netatalk proper and move towards a monorepo.

The benefits for doing this would be:

• Coupling between netatalk release versions and webmin module release versions
• Better chance that the module is kept up to date in the future
• Enables the netatalk build system to build and install the module in tandem with netatalk proper (when webmin is detected)
• Most potently, the build system can modify the module's config file on the fly to match the actual prefixes of binaries and config files

https://github.com/Netatalk/netatalk-webmin/blob/main/config

Drawbacks:

• More code in the repo that has to be maintained...

[rdmark]

A few requirements:

• Create an artifact that is a tarball with the webmin module dir structure (in parallel to the netatalk release tarball)
• When webmin is detected, run the install_module.pl script to install said tarball
• Support RH, Debian, and Solaris webmin install locations

Standard install locations:

• Debian: /usr/share/webmin
• RH: /usr/libexec/webmin
• Solaris: /opt/webmin

[rdmark]

Alternative approach: Make webmin a submodule of the main repo, and have a custom script that modifies the config file and runs its build system.

[rdmark]

Discarding this for now. Lots of complexity for little gain.

[rdmark]

Achieved with https://github.com/Netatalk/netatalk/pull/1532