[v2] [1/X] ApolloStore async Read/Write lock

[AnthonyMDev]

Creates a ReaderWriter using SwiftAtomics that allows for multiple parallel reads while locking for writes.

This will replace the current barrier queue for ApolloStore. Usage of this will be implemented in stacked PR.

[svc-apollo-docs]

⚠️ Docs preview not attached to branch

The preview was not built because the PR's base branch v2 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: b87e5157d246455d6d20d5a1

[calvincestari]

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