Investigate to see if geoserver rest api need to have the same method when uploading data to geoserver

[ywkim312]

Currently, there are two different way of uploading the data to geoserver in geoserver rest api class. One is directly post dataset with the creation of datastore and layer at the same time and the other is create datastore first then create a layer in the datastore. The first method is much clean and simpler and should be faster even though the difference should be really small, but this doesn't work when renaming the geopackage file name to dataset id. The second one is much more complicated in terms of code structure but it works. We need to check to keep these two methods or just making every method to the second on in terms of the code structure's unity.