Update key for session context field in attributes

[kshitiz-okahu]

Proposed changes

The key for persisting sessions in attributes has been simplified as discussed in #25

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

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Further comments

If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered, etc...

[oi-raanne]

as context is a first class object in telemetry, it can confuse the users as json path to fetch would be context.<property name> .My suggestion would be to use either 'invocation' or not to add any prefix

[akshay-okahu]

• from perspective of capturing and querying these attributes in prompt API, should be fine either way
  • if the span of these attributes is fixed, like root span for eg, it would be easier for prompt API implementation
  • since these attributes are inserted in all spans, including root span, so prompt API implementation should be fine
• some prefix might be helpful to determine if the attribute came from framework vs custom attribute inserted by user, though not sure if this is needed
  • some possible prefix alternatives could be: state, session, trace

[kshitiz-okahu]

changed to session.{property_name}