Document and update Cauldron behaviors / utils

[scurker]

We have a few Cauldron utilities that are undocumented but exported:

cauldron/packages/react/src/index.ts

Lines 141 to 143 in d6bcd11

	export { default as AriaIsolate } from './utils/aria-isolate';
	export { default as focusableSelector } from './utils/focusable-selector';
	export { default as useDidUpdate } from './utils/use-did-update';

Since these are part of our public api, we cannot significantly modify these exported utils without potentially causing breaking changes. We should properly document any "behaviors" we want to include as a part of Cauldron as well as set the expected usage of these utilities. This will require a proposal that should include:

• How these behaviors should be written (hooks vs non-hooks)
• When a function should be written as a behavior
• How these behaviors should be exported from Cauldron

It may be expected that removing some of these existing utilities that may not need to be exported may result in breaking changes and should be included in the proposal on how we will minimize the risk.