Retry When Network is Down at Startup

[mwaeckerlin]

• Updates dependencies to latest (React 18)
• Adds a retry option in milliseconds to the provider: Retries to read the JSON file and to initialize the service when it is down at startup.
• Adds an internal status ready that is set to false when API init failed.
• API calls are only executed, once ready is true

Tests still succeed, but I haven't added new tests for the new feature.

See: #52

[mwaeckerlin]

Somehow does not work that way... Could eventually be a problem of calling setState in a timed function?