Use the Filesystem Hierarchy Standard (FHS) for deployments and artifacts

[gustavovalverde]

Motivation

Linux has its own filesystem convention, which is standard and considered by most sysadmins when creating products, OS-level restrictions, and even when taking security measures.

We should respect this convention for compatibility with different deployment mechanisms, and when high-security standards are being in placed (most directories are being restricted)

A good example is the Container-Optimized OS used by Google: https://cloud.google.com/container-optimized-os/docs/concepts/disks-and-filesystem#working_with_the_file_system

Specifications

Filesystem Hierarchy Standard - v3.0: https://refspecs.linuxfoundation.org/FHS_3.0/fhs-3.0.html
Linux man for hier: https://man7.org/linux/man-pages/man7/hier.7.html

Related Work

#3344

[teor2345]

We'll need to make the zebra changes in #1894 to fully support the file system hierarchy standard. But that's a breaking change.

Did you want to schedule both changes for an upcoming sprint?
(They are not required for the stable release candidate, but we should do them before the stable release.)

[teor2345]

We want to check this all got done, then close it.