Handle exclude lists in a test run request

[karthiknadig]

See here for how exclude list is generated: microsoft/vscode#130522

1. unittest: The underlying test adapter deals with testcases only. All we need to do is pass the right set of test case nodes (leaf nodes) to the runner in the extension.
2. pytest : With the current test adapter we need to do additional work to prune the test tree to the a set of tests nodes that have no children in them that are in the exclude list. We can then pass the pruned nodes to the runner in the extension. A better approach here would be to update the test adapter to handle test runs based on the leaf nodes. This will also allow us to report test run progress, instead of running everything in bulk.

[eleanorjboyd]

Hello! I have reviewed this issue and given the architectural changes of the testing rewrite, this issue should no longer exist on the rewrite. Therefore I am going to close this issue but please comment or open a new issue if you are still seeing a problem when you try this yourself!

To use the rewrite yourself just add ”python.experiments.optInto": ["pythonTestAdapter"] to your user settings. You can confirm you have the rewrite enabled by setting your log level to trace, via the Developer: Set Log Level command in the command palette. Then check to see if Experiment 'pythonTestAdapter' is active is in your python logs.

Thanks!