parseTenantConfig() only allowed configuring a defined set of options,
and KMSs were not able to re-use the implementation. Now, the function
parses the ConfigMap from the Tenants Namespace and returns a map with
options that the KMS supports.
The map that parseTenantConfig() returns can be inspected by the KMS,
and applied to the vaultTenantConnection type by calling parseConfig().
Signed-off-by: Niels de Vos <ndevos@redhat.com>