Update documentation structure and start migrating to markdown (#934)

Starts structuring the documentation library usage into Tutorials, Guides, Explanations and Reference.
Continues migrating new docs from rst to markdown.
Extends the test framework discovery mocks to allow easy writing and testing of code examples.

kasa/tests/device_fixtures.py

@@ -396,6 +396,13 @@ async def get_device_for_fixture_protocol(fixture, protocol):
             return await get_device_for_fixture(fixture_info)
 
 
+def get_fixture_info(fixture, protocol):
+    finfo = FixtureInfo(name=fixture, protocol=protocol, data={})
+    for fixture_info in FIXTURE_DATA:
+        if finfo == fixture_info:
+            return fixture_info
+
+
 @pytest.fixture(params=filter_fixtures("main devices"), ids=idgenerator)
 async def dev(request) -> AsyncGenerator[Device, None]:
     """Device fixture.