[Uptime] Create generic testing utilities

[dominiqueclarke]

When testing, we commonly need wrappers context providers like Redux, Intl, and Kibana Context. A few of these helpers currently exist, but it appears that they may not meet all the common use cases as we've manually added wrappers in a handful of tests.

Ideally, newly added testing utilities would be generic enough to be used with any testing library, consisting of a simple wrapped component that can then be rendered with the testing library of your choice, be it enzyme, react testing library, or otherwise.

[elasticmachine]

Pinging @elastic/uptime (Team:uptime)