feat: Store.request

[runspired]

Implements Store.request making use of Cache.put and Cache.peekRequest.

This PR:

• Store.request
• Store.lifetimes support
• Store.requestManager docs/types
• ember-data auto-configures RequestManager
• findAll as request op
• query as request op
• queryRecord as request op

ToGo:

• findRecord as request op
• saveRecord as request op
• findBelongsTo as request op
• findHasMany as request op
• enforce immutability in dev
• handle error documents in cache
• handle meta documents in cache
• lots of tests
• no seriously, lots of tests
• update docs for RequestManager.useCache
• implement new Collection mode to properly reflect ResourceDocument
• ensure single-resource-document requests are notified when data changes
• determine Cache "mutability" of CollectionResourceDocument
• add tests for enhancing context.request in RequestManager before calling next

Other Notes:

• clarify intended Error handling mechanisms/propagation
• update RFC for RequestManager.useCache
• update RFC for lifetimes.isSoftExpired/isHardExpired
• update RFC for rename data => content