wip: otel instrumentation enhancements

[adrianlyjak]

1. Add shutdown method to destroy all spans, to be e.g. called on SIGTERM to close out spans
2. add generic export/import dict methods for passing trace context across a data boundary (network, retry).
3. adjust otel integration so that tags set attributes
4. Adjust otel integration so that the operation name is a non-unique value, (not the span full id), so you can search on it, etc. This takes the same approach as phoenix/openinference does in their integration with llama_index, but perhaps in the future it might make sense to push more otel concepts into the core, such as name here.

Example crash/recover running a durable workflow and a killed pod:

shutdown error details, tags as attributes (auto prefixed with llamaindex. to not overlap. Can set tags like foo.bar and it will not be prefixed, and assume you know what you are doing. Might be able to use to support using semantic conventions in the future)

Search on name attribute