[KSambaShare] Add unit test for "net usershare info" parser

Summary:
The existing tests depend on the runtime environment, i.e. they read
the share list from the developers usershares. In case the account
has no usershares, the parser is not tested.

Inject some test data for several test cases into the parser.

As the KSambaSharePrivate::parse() method is not visible from the
shared library by default, link statically to it.

Depends on D16464
Depends on D16465

Test Plan: make && ctest

Reviewers: Frameworks, broulik, apol

Reviewed By: apol

Subscribers: kde-frameworks-devel

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D16466