[v2] [7/X] Query Watcher Task Local Context Id

[AnthonyMDev]

GraphQLQueryWatcher now uses a Task Local value to keep track of its context identifier. This encapsulates the deduplication of watcher re-fetches on the watcher itself.

This encapsulation allows us to remove the contextIdentifier field from NetworkTransport, ApolloClient, and other associated APIs.

[svc-apollo-docs]

⚠️ Docs preview not attached to branch

The preview was not built because the PR's base branch unit-tests is not in the list of sources.

An Apollo team member can comment one of the following commands to dictate which branch to attach the preview to:

• !docs set-base-branch main

Build ID: 10621163a2723ee77d5609ed

[calvincestari]

Going to slowly make our way through these during the week - there is a lot to review. 😓