Two federation build contexts after core #145

[Aukevanoost]

native-federation/native-federation-core#145 builds shared mappings apart from exposed modules,
so setup()/build() now run once per mapping bundle plus once for mapping-or-exposed, each
with its own Angular context. Nothing breaks until the ~4.6.0 core range is bumped.

1. updateFederationTsConfig replaces files wholesale
   (src/tools/esbuild/update-federation-tsconfig.ts:57). Each context's setup() overwrites
   files with only its own entry points, so the mapping entries drop out of the program. In
   watch mode, a mapping that only files pulls in rebuilds without error but keeps serving its
   old content.

   Fix: write the union of all Angular contexts' entry points into files.

2. Only mapping-or-exposed is disposed (src/builders/build/builder.ts:532), so the mapping
   contexts never reset Angular's shared TS state before the app build (buildForFederation corrupts globalSharedCompilationState, causing "polyfills.ts missing from TypeScript compilation" on Linux #47). The no-arg
   dispose() also stops esbuild, which the app build still needs.

   Fix: dispose every isMappingOrExposed context, leaving esbuild running.

A shared SourceFileCache across the contexts needs no change: Angular shares one the same way
between its browser, polyfills and server bundles.

[Aukevanoost]

Fixed in #139. It waits for Angular 22.2 before it can be released.