Adopt the XDG Base Directory Specification

[paulbes]

Background

The XDG base directory specification defines a set of environment variables for controlling where configuration and cache files should be written to.

This makes is possible for the end users to better control where the okctl artefacts are written to. This is useful for ensuring that important configuration files are backed up automatically, while cached binaries are not.

Details

$XDG_DATA_HOME

Defines the base directory relative to which user specific data files should be stored. If $XDG_DATA_HOME is either not set or empty, a default equal to $HOME/.local/share should be used.

$XDG_CONFIG_HOME

Defines the base directory relative to which user specific configuration files should be stored. If $XDG_CONFIG_HOME is either not set or empty, a default equal to $HOME/.config should be used.

[paulbes]

golang/go#29960