Support url/external method in create_coveragestore

[yuhangch]

This is a feature request.
In GeoServer Rest API doc : coveragestores

The upload method. Can be "url", "file", "external". “file” uploads a file from a local source. The body of the request is the file itself. “url” uploads a file from a remote source. The body of the request is a URL pointing to the file to upload. This URL must be visible from the server. “external” uses an existing file on the server. The body of the request is the absolute path to the existing file.

I assume that the method create_coveragestore has a parameter , which is set to file by default, and can be set to url or external.

[iamtekson]

Hey @yuhangch, I know, it is been a long time, I didn't respond to your issue. But anyway, As you said, the create_coveragestore functionality is currently working for the file only. But if you have any idea about setting URL or external as the coveragestore parameter, Please send the Pull request to this repo. The create_coveragestore function is available here