Make possible to configure the path for mounting extra ConfigMaps/Secrets individually

[gazarenkov]

For the time twe only can define single path for all the extra files.
spec.application.extraFiles.mountPath which is not convenient for the case when particular mounted file should be located in certain place (e g CA).
Proposal: to add 'path' to single ConfigMap/Secret entry.
Path can be absolute or relative to spec.application.extraFiles.mountPath (or to global default if not defined)