feature: Weather API definition.

[panaaj]

Version 2 Weather API:

Goals:

• Implement an API (with OpenAPI definition) for accessing weather information sourced from various weather services (i.e. NOAA, OpenWeather, Open-Meteo, etc).
• Support multiple weather providers
• Provide access to observation, forecast and warnings.

Features:

• [x] API operations under the path /signalk/v2/api/weather
• [x] List and switch between providers/signalk/v2/api/weather/providers
• [x] Send notifications for weather warnings

Related	Link
Specification	https://github.com/SignalK/specification/pull/662
Open-Meteo Provider Plugin	https://github.com/SignalK/openmeteo-provider-plugin