Test Plan Implementation - Integration Tests: swift-plugin

[michael-weng]

We already have integration tests for the task providers, but just need one to cover the user facing commands.

What we want to test for:

• swift.runPluginTask shows up and can be executed by user when under the right command_plugin file
• swift.runPluginTask command return appropriate tasks from different sources (provided by extension or resolved from tasks.json)

[award999]

@michael-weng can you add the plan of what needs to be tested

[michael-weng]

@michael-weng can you add the plan of what needs to be tested

Done.