Make legacy ErrorEvent / ToolEvent part of public API. (#823)

Author: tcdent

agentops/__init__.py

@@ -4,6 +4,7 @@
 from .sdk.commands import record as sdk_record, start_span as sdk_start_span, end_span as sdk_end_span
 from .semconv.span_kinds import SpanKind
 import agentops.legacy as legacy
+from agentops.legacy import ErrorEvent, ToolEvent
 
 # Client global instance; one per process runtime
 _client = Client()