Delete Libraries/JSInspector (#49019)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/49019

Removes the `JSInspector` class and its dependencies.

- This was related to the legacy `ReactCommon/inspector/` subsystem (D4021490) — which added a compat layer from JavaScriptCore to CDP for an earlier version of Chrome debugging.
- The JS components of this system (`JSInspector.js`, `NetworkAgent.js`) were added in D4021516.

`ReactCommon/inspector/` has since been deleted and these components are no longer load bearing.

- We intend to replace this logic (at least, the archaic `XHRInterceptor` behaviour, which worked at one point) with native debugger `Network` domain support in our C++ layer.

**Changes**

- Remove all modules under `Libraries/JSInspector/`.
- Remove all `XHRInterceptor` call sites.
- Remove the `JSInspector.registerAgent()` mount point in `setUpDeveloperTools.js`.
- Exclude `Libraries/Core/setUp*` from `public-api-test` (these are side-effect setup files with no exported API).

Changelog:
[General][Breaking] - Remove legacy Libraries/JSInspector modules

Reviewed By: christophpurrer

Differential Revision: D68780147

fbshipit-source-id: 3d11cc89886a91055e6b69ac6f0609c288965801