Add initial feature/UI customisations for profiling builds

[huntie]

Summary

Initial feature and UI customisations triggered when connected to a React Native profiling build (under development). Depends on facebook/react-native#47966.

Changes:

• Adds FuseboxProfilingBuildObserver, which dynamically configures available DevTools features when a profiling build is identified.
• Statically disables sub-features of the Performance panel (including CPU throttling, Settings pane).

Notes:

• Includes a first run experience as shown, necessary when switching experiment settings at runtime. On subsequent launches, the Performance panel is permanently enabled (dev and profiling builds).

Test plan

[Meta internal] See D66501770.

• This change maintains backwards compatibility with previous Local Storage data (if modifying settings, experiments, or other persisted client state).

Upstreaming plan

• This commit should be sent as a patch to the upstream devtools-frontend repo. I've reviewed the contribution guide.
• This commit is React Native-specific and cannot be upstreamed.