Provide OpenTelemetry Resource as a bean

[mhalbritter]

Our current OpenTelemetryAutoConfiguration uses the io.opentelemetry.sdk.resources.Resource inside the SdkTracerProvider bean method. To make it easier to use this resource for other OpenTelemetry components, we should expose it as a bean.

Additionally, we should add some properties to let users configure resource attributes.

[mhalbritter]

I have something sketched out here: ccf9fc7

[mhalbritter]

The new resource attributes live under management.opentelemetry.resource-attributes.

There are management.otlp.metrics.export.resource-attributes, which we should deprecate in favor of the new ones.

[mhalbritter]

I've flagged this as team meeting so that we can discuss the problem with the two OpenTelemetryAutoConfigurations: There's one for the OpenTelemetry and Resource bean and there's another for the tracing part. We can't rename the old one as this will break users, and we need to find a good name for the new one. I've put in OpenTelemetryInfrastructureAutoConfiguration as a placeholder. Changes are in this branch: https://github.com/mhalbritter/spring-boot/tree/mh/36544-provide-opentelemetry-resource-as-a-bean