Feature/support truenas scale

[jeje42]

Hi,

After migrating to Truenas Scale, I experienced some issues with generating disk status reports.

This suggestion PR allows creating reports from Scale systems.
I tried to keep compatibility with Core by isolating system specific commands into the "system-specific-aliases" script.

Also tried to make the structure more flexible with the following changes:

• separating the configuration into .env file
• isolating the email part from the rest into "email-writing" file, however this requires more work into another PR if this concept is approved. Goal could be to decouple the main logic from email specific code.

Unfortunately I am no more running Core on a daily basis, I should create a VM with Core soon to test on my own but any feedback is welcome :).