Also refactor New and Get to return pointers to match BaseConf methods.
This makes calling the methods immediately on the return values of the
constructors easier.
Also move config.ConfigFile to buildconfig.go.in. ConfigFile is still
used by wwctl as a default config file to reference; but it is removed
from other locations now.
Removed Persist, as nothing called it.
Signed-off-by: Jonathon Anderson <janderson@ciq.co>
The caching functionality of nodes.conf, and the optional persistence
functionality that came with it, appears to have been preventing
actually writing the configuration to disk in all cases. This change
fixes the ability to write to nodes.conf.
Somewhat opinionatedly, this change removes the caching functionality of
nodes.conf. The tests have also been updated to use real files for i/o
rather than tying into the caching system, making them more accurately
test the ability of Warewulf to actually read and write its
configuration.
Fixes#779
Signed-off-by: Jonathon Anderson <janderson@ciq.co>
