Don't require local resources and getters to have globally unique names

[matthew-white]

This PR continues the work of #1050 in trying to simplify requestData. #1050 removed Pinia, making it such that different local resources are more independent of one another. Under Pinia, two local resources with the same name (created at different times) would share the same Pinia store. We've now removed these shared Pinia stores, but there is still a constraint on local resources: it's not possible for two local resources created at the same time to have the same name, even if they are created in different components. In other words, resource names must be globally unique, even for local resources.

My goal in this PR is to make local resources and getters as similar to provide/inject as possible. That's already the mechanism that they're using under the hood. provide/inject is happy to shadow an existing value with the same name. Now requestData will be fine if a local resource or getter shadows one from an ancestor component. It's not like we have a pressing need for shadowing, but by allowing it, we can simplify requestData. For example, we can consolidate all cleanup in onUnmounted() rather than using onUnmounted() for some things and onBeforeUnmount() for other things. I also think that allowing shadowing clarifies the mental model around local resources: local resources should be fully independent of one another.

Before submitting this PR, please make sure you have:

• run npm run test and npm run lint and confirmed all checks still pass OR confirm CircleCI build passes
• verified that any code or assets from external sources are properly credited in comments or that everything is internally sourced

[matthew-white]

Notes from interactive review

[matthew-white]

getters[name] = ref;

[matthew-white]

Do we even need getters anymore? They seem rarely used. We could probably just use provide/inject instead. Let's see about removing them in a follow-up PR.