This change allows users to reference environment variables using Go template format, like {{ .EnvName }}
Moved the previous file test code to file_suite_test.go.
Add a direct write to handle management.json write operation.
Remove empty configuration types to avoid unnecessary fields in the generated management.json file.
Force to use the proper temp dir
If we do not define the configDir then the Go
create a random temp dir for copy routine.
It is not optimal from security purpose.
* Create temp file before saving data
On the event of full disk, we may encounter the case where the
destination file get replaced by an empty file as the
ioutil.WriteFile truncates the destination before write.
* Close the tempFile instance before moving it
* Blacklist Wireguard interfaces for ICE checks
