Manages read-your-write tokens. The manager works based on conditions & tokens.

Tokens are stored in a nested map indexed by a unique id (e.g. `onesignalId`) and a token key (e.g. `USER`).

This allows us to track tokens on a per-user basis (e.g. handle switching users).

Conditions work by creating a blocking mechanism with customizable token retrieval until a pre-defined condition is met (e.g. at least two specific tokens are available).

Also allows extensibility for future applications to control offset blocking mechanism in consistency use-cases.

Inject ConsistencyManager where it will be used.

Motivation: custom condition to block token retrieval until condition is met.

We then return the newest token

Motivation: support passing values as headers, add comments

Motivation: need the offsets to be available to set in the ConsistencyManager

Motivation: the IAM fetch call (`listInAppMessages`) will include the rywToken, retryCount, & secondsSinceAppOpen (tracked on backend)

We update the request & related code here.

Handle retry logic

Motivation: we want to update the user as soon as possible in order to not delay IAM fetch

Motivation: to be used to index read your write tokens specific to the IamFetch consistency use case

Motivation: the executors call the respective backend services who's result will include the token value. We then hold in memory via `setRywToken`

Motivation: offset, secondsSinceAppOpen, & retryCount will be sent as headers

…l headers