Refactor ProfilerContext to use reducer instead of multi-state

The `ProfilerContext` is currently comprised of several pieces of related state, each managed with `useState`. This necessitates awkward checks like [this](https://github.com/bvaughn/react-devtools-experimental/blob/4697f5b37967b85b2c844044aeebb5b1a740875d/src/devtools/views/Profiler/ProfilerContext.js#L126-L131) or even worse like [this](https://github.com/bvaughn/react-devtools-experimental/blob/4697f5b37967b85b2c844044aeebb5b1a740875d/src/devtools/views/Profiler/SnapshotSelector.js#L62-L73) or [this](https://github.com/bvaughn/react-devtools-experimental/blob/source/src/devtools/views/Profiler/Profiler.js#L71-L83). This context should be refactored to use a single reducer (`useReducer`) like `TreeContext`. This is a bit more involved at the moment because of suspense and the `ProfilerContext` being higher level than the suspense cache. Although maybe we could work around this by using some sort of [subscription](https://github.com/bvaughn/react-devtools-experimental/blob/4697f5b37967b85b2c844044aeebb5b1a740875d/src/devtools/views/Profiler/ProfilerContext.js#L118-L124)? See related issues like #16441 and commit [4697f5b](https://github.com/bvaughn/react-devtools-experimental/commit/4697f5b37967b85b2c844044aeebb5b1a740875d).