Read tracing API data lazily

[rm-openai]

A common complaint is that people load their API keys using dotenv:

import agents # imports tracing by default

load_dotenv()

This causes issues, because by the time you load your dotenv, the batch processor has already read the API key.

Let's lazy load it, so it's deferred to when the processor actually needs the key.

[stevenheidel]

consider using built-in functools.cached_property from python 3.8 rather than managing state yourself:

Suggested change

	def _lazy_read_api_data_from_env(self):
	if self._lazy_read_complete:
	return
	self._lazy_read_complete = True
	if not self.api_key:
	self.api_key = os.environ.get("OPENAI_API_KEY")
	if not self.organization:
	self.organization = os.environ.get("OPENAI_ORG_ID")
	if not self.project:
	self.project = os.environ.get("OPENAI_PROJECT_ID")
	@cached_property
	def api_key(self):
	return self._api_key or os.environ.get("OPENAI_API_KEY")
	@cached_property
	def organization(self):
	return self._organization or os.environ.get("OPENAI_ORG_ID")
	@cached_property
	def project(self):
	return self._project or os.environ.get("OPENAI_PROJECT_ID")