Rework otel with buffer and restructuring with TraceTree.

[FrancesTwisk]

Renewed logic for processing spans into reports.

1. Spans get collected per traceId in an buffer.
2. After a certain time-out traces get removed from buffer and processed.
3. For processing traces get restructured, for this a new class TraceTree is used which represents the parent-child relationships between spans. When a TraceTree done with structuring, Depth-First Search algorithm is used to create start- info- and endpoints for each span in an trace.