RN: Check ReactSafeMobileConfig Dependents for MobileConfig References

Summary:
Modifies `js1 build buckfiles` to also parse files that depend on `ReactSafeMobileConfig` for MobileConfig references.

That module was introduced in {D30470489}.

This fixes a bug where the MobileConfig reference in `ReactNativeInternalFeatureFlags` is not being correctly defined via Metro Buck.

Changelog:
[Internal]

Reviewed By: rickhanlonii

Differential Revision: D30815779

fbshipit-source-id: 156b0838fe47e7ab42c62258a1401875690813a6

BUCK

@@ -687,7 +687,6 @@ rn_library(
         ],
     ),
     labels = ["supermodule:xplat/default/public.react_native.core"],
-    skip_processors = True,  # Don't anticipate routes or fbicon here
     visibility = ["PUBLIC"],
     deps = [
         "//xplat/js:node_modules__abort_19controller",