Create a basic SunSpec window

[altendky]

This goes along with #25. As a first exercise in integrating SunSpec functionality into the GUI let's start simple. The window should be able to do the following things.

• Allow user specification of a Modbus TCP server to connect to
• Be able to cyclically read a user specified data point from the server
• Be able to write a user specified data point to the server on user request

Or, maybe we want to break this up into three tickets... Anyways, there is existing code in the tests that shows creation and connection of a SunSpec client outside of Qt.

ssst/src/ssst/_tests/conftest.py

Lines 66 to 82 in 46232ec

	@pytest.fixture(name="unscanned_sunspec_client")
	async def unscanned_sunspec_client_fixture(
	sunspec_server: SunSpecServerFixtureResult,
	) -> typing.AsyncIterator[ssst.sunspec.client.Client]:
	async with ssst.sunspec.client.open_client(
	host=sunspec_server.host,
	port=sunspec_server.port,
	) as client:
	yield client
	@pytest.fixture(name="sunspec_client")
	async def sunspec_client_fixture(
	unscanned_sunspec_client: ssst.sunspec.client.Client,
	) -> ssst.sunspec.client.Client:
	await unscanned_sunspec_client.scan()
	return unscanned_sunspec_client