Bug 1004977 - Datasource configuration changes SHOULD NOT require a comp...

...lete reload/restart of EAP

"Enabled" attribute is no longer an editable configuration property (it will still be available on (xa-)datasource creation).
Instead, users will have to use the "Enable"/"Disable" operations.

"Enable"/"Disable" definitions have been changed to include a new "allow-resource-service-restart" property, defaulting to false.
If set to true, the corresponding management request header will be added. This allows to disable/enable a datasource without a server reload.

The datasource component update configuration logic has been enhanced to send only configuration changes. It requires an extra request
to read the current datasource config, but it avoids a server reload or datasource disable/enable cycle if the user only wants to
change a set of properties which do not require it.

Also, a new specific component class has been added for the datasources subsystem resource type. It used to be shared with the (xa-)datasource component.
While in the beginning it probably was easier to have a single class for code sharing between the "Create Child Resource" process and the "Update Configuration Process",
the (xa-)datasource component logic has become quite complex so it's safer to have separate component classes.

Eventually, the plugin descriptor has been updated to document that some (xa-)datasource properties cannot be unset if they already have a value.