Api refactor

[thorinaboenke]

this PR relates to issue #106

• refactors RemoteAttackmateClient and attackmate-api-server into separate repositories
• makes attackmate exectors async (sliver executor used get_event_loop and run_until_complete, which is not possible with a webserver/already running event loop)

Additionally:

• fixes deprecation warnings @model_validator #200 (model_validator deprecation warning)
• refactors remote config for multiple connections multiple connections in configs for remote attackmate #199
• adds is_api_instance variable add is_api variable #191