feat(playground): parse span attribute `llm.input_messages` for playground span replay (#4906)

* begin building zod schemas for llm attributes

* feat(playground): parse span input messages

* move to utils, update role

* update initial instance id

* update id generation, add todo, add test files

* add tests

* memoize

* move jest-canvas-mock to dev dependencies

* update span not found error message

* parse roles as strings and corece to ChatMessageRole

* update ChatRoleMap comment

* fix typos

* update prop type to be InitialPlaygroundState

* update naming

* fix naming conflict