refactor[react-devtools]: rewrite context menus

[hoxyq]

Summary

• While rolling out RDT 5.2.0 on Fusebox, we've discovered that context menus don't work well with this environment. The reason for it is the context menu state implementation - in a global context we define a map of registered context menus, basically what is shown at the moment (see deleted Contexts.js file). These maps are not invalidated on each re-initialization of DevTools frontend, since the bundle (react-devtools-fusebox module) is not reloaded, and this results into RDT throwing an error that some context menu was already registered.
• We should not keep such data in a global state, since there is no guarantee that this will be invalidated with each re-initialization of DevTools (like with browser extension, for example).
• The new implementation is based on a ContextMenuContainer component, which will add all required contextmenu event listeners to the anchor-element. This component will also receive a list of items that will be displayed in the shown context menu.
• The ContextMenuContainer component is also using useImperativeHandle hook to extend the instance of the component, so context menus can be managed imperatively via ref: contextMenu.current?.hide(), for example.
• Changed: The option for copying value to clipboard is now hidden for functions. The reasons for it are:
  • It is broken in the current implementation, because we call JSON.stringify on the value, see packages/react-devtools-shared/src/backend/utils.js.
  • I don't see any reasonable value in doing this for the user, since Go to definition option is available and you can inspect the real code and then copy it.
  • We already filter out fields from objects, if their value is a function, because the whole object is passed to JSON.stringify.

How did you test this change?

Works with element props and hooks:

• All context menu items work reliably for props items
• All context menu items work reliably or hooks items

https://github.com/facebook/react/assets/28902667/5e2d58b0-92fa-4624-ad1e-2bbd7f12678f

Works with timeline profiler:

• All context menu items work reliably: copying, zooming, ...
• Context menu automatically closes on the scroll event

https://github.com/facebook/react/assets/28902667/de744cd0-372a-402a-9fa0-743857048d24

Works with Fusebox:

• Produces no errors
• Copy to clipboard context menu item works reliably

https://github.com/facebook/react/assets/28902667/0288f5bf-0d44-435c-8842-6b57bc8a7a24