feat(langfuse): enhance trace capabilities by default with the types that langfuse offers

[Hansehart]

Is your feature request related to a problem? Please describe.
Currently when using the langfuse connector, everything is declared as span or generator.

Describe the solution you'd like
Adding support for embedders is included in #2471, but there are more types like:

"span",
"agent",
"tool",
"chain",
"retriever",
"evaluator",
"guardrail",

https://github.com/langfuse/langfuse-python/blob/main/langfuse/_client/constants.py

There are some compatible type defintions between Haystack and Langfuse. From my POV agent, tool, chain, retriever, evaluator could be an useful enhancement.

Describe alternatives you've considered
Extending SpanHandler base class and write custom rules. However an plug-and-play approach could be beneficial to improve the adoption of this framework.

Additional context
It works also without, but everything is a span or generator or with custom handler

[vblagoje]

Reopening automatic close until we implement:

• retriever
• embedding

See https://langfuse.com/docs/observability/features/observation-types for more details

Already implemented and released:

• agent
• tool

with #2490 PR