This change splits out discovery fields from JoinConfiguration by performing
the following changes:
- Introduce a BootstrapTokenDiscovery structure, that houses configuration
options needed for bootstrap token based discovery.
- Introduce a FileDiscovery structure, that houses configuration options
(currently only a single option) needed for KubeConfig based discovery.
- Introduce a Discovery structure, that houses common options (such as
discovery timeout and TLS bootstrap token) as well as pointer to an instance
of either BootstrapTokenDiscovery or FileDiscovery structures.
- Replace the old discovery related JoinConfiguration members with a single
Discovery member.
This change is required in order to cleanup the code of unnecessary logic and
make the serialized JoinConfiguration more structured (and therefore, more
intuitive).
Signed-off-by: Rostislav M. Georgiev <rostislavg@vmware.com>
