Create basic unit tests and document what's expected to work

[noklam]

In general the extension leverage kedro as much as possible, there are small different for ergonomics reason which are not documented very clearly.

As the first step, I want this behavior to be test explicitly and create some unit tests for utils function in lsp_server.py which are easier to test. We do not have to test the Kedro components since this is covered already, instead focus on the special things about vscode extension.

for example:

• _is_pipeline
• _get_conf_path
• _get_parameter_location
• etc...

[noklam]

Closed as combined with #20