ST6RI-836 Add option that allows changing the API basePath in a running Jupyter kernel

[TheKorpos]

In the current implentation of the Jupyter kernel the REST API base path is specified as part of the deployment process: either during the kernel installation by using --api-base-path or by using an environmental variable.

This PR adds the %api-base-path [<BASE PATH>] magic command that allows users to change the API base path in the running kernel.

[seidewitz]

%api-base-path is an awkward name for a command. How about something like %repo instead. The help text should then say:

Usage: %repo [<BASE PATH>]

If <BASE PATH> is not given, print the current repository base path.
If <BASE PATH> is given, set the repository base path.

<BASE PATH> is a URL giving the API base path for the repository access by the %projects, %publish and %load commands. 
For example: https://my.domain.com/sysml_repo

[TheKorpos]

%api-base-path is an awkward name for a command. How about something like %repo instead. The help text should then say:

Usage: %repo [<BASE PATH>]

If <BASE PATH> is not given, print the current repository base path.
If <BASE PATH> is given, set the repository base path.

<BASE PATH> is a URL giving the API base path for the repository access by the %projects, %publish and %load commands. 
For example: https://my.domain.com/sysml_repo

Hi @seidewitz,
I've udpated the magic command name and help strings.

For the example URL I used the default value (http://sysml2-dev.intercax.com:9000), it's more consistent with the new help strings, and default values we used in ST6RI-178.

Also, I removed the part 'The api base path is:' from the output of this command so now it simply prints the current base path.

[seidewitz]

For the example URL I used the default value (http://sysml2-dev.intercax.com:9000), it's more consistent with the new help strings, and default values we used in ST6RI-178.

I specifically do not want to put a real domain in the help text. The Intercax deployment will not be the default forever, and may even change in the near future. And the default should particularly not be the sysml2-dev server. This is for internal development use, and the URL is not supposed to be public.

[TheKorpos]

I specifically do not want to put a real domain in the help text. The Intercax deployment will not be the default forever, and may even change in the near future. And the default should particularly not be the sysml2-dev server. This is for internal development use, and the URL is not supposed to be public.

I see. I changed it to the one you wrote.