add span stacktrace config option

[SylvainJuge]

Description:

Span stacktrace module can't use autoconfiguration for now as it relies on a strict ordering of the span processors. The addition of OnEnding callback would unblock this but it's not available yet (https://github.com/open-telemetry/opentelemetry-java/pull/6367).

While autoconfiguration is still not supported, this PR adds a way to provide a ConfigProperties for configuration, which allows to

• define configuration option and default value
• implement configuration in a consistent way across usages

Configuration option name otel.span.stacktrace.min.duration Default value: 5ms