Python code cleanup

These changes should not change any functionality.

In code:

- Added async keyword to CryptoSystem::kind since it's actually implemented async
- Removed unused socket import in json_api

In tests:
- Removed unused imports
- Removed unnecessary return statements
- Removed unused variables
- Cleaned up some spacing to match PEP-8
- Changed many comparisons to match PEP-8
- Use ValueSubKey classes instead of integers to keep types in line

veilid-python/tests/conftest.py

@@ -4,9 +4,9 @@ from typing import AsyncGenerator
 
 import pytest
 import pytest_asyncio
-from veilid.json_api import _JsonVeilidAPI
 
 import veilid
+from veilid.json_api import _JsonVeilidAPI
 
 
 pytest_plugins = ("pytest_asyncio",)
@@ -22,7 +22,6 @@ async def api_connection() -> AsyncGenerator[_JsonVeilidAPI, None]:
         api = await veilid.api_connector(simple_update_callback)
     except veilid.VeilidConnectionError:
         pytest.skip("Unable to connect to veilid-server.")
-        return
 
     async with api:
         # purge routes to ensure we start fresh