FrameworkMockConfigurator: real enableX helpers can silently un-mock a pinned module

[odinr]

Problem

FrameworkMockConfigurator._pin wraps a built-in module's configure factory so it always returns the same instance, then registers it via this.addConfig({ module: pinned }). ModulesConfigurator.addConfig re-registers modules by name on a last-write-wins basis: when a later addConfig call arrives for the same module name (e.g. an application calling the module's real enableX/configureX helper — not its mock-specific counterpart — against a FrameworkMockConfigurator), it removes the pinned module's callbacks and installs the real, unpinned configure factory instead.

The result: initialization builds a fresh, real (unmocked) configurator instance for that module, while the corresponding accessor on FrameworkMockConfigurator (e.g. .telemetry, .msal, .http) keeps returning the stale pinned mock — configuration and reads silently drift apart.

This affects every module pinned by FrameworkMockConfigurator: msal, serviceDiscovery, http, services, context, and telemetry.

Reproduction sketch

const fusion = await mockFramework((configurator) => {
  // enableTelemetry is the REAL helper, not enableTelemetryMock
  enableTelemetry(configurator, (builder) => builder.setMetadata({ app: 'demo' }));
});

// configurator.telemetry.adapter still refers to the pinned mock,
// but fusion.modules.telemetry is now backed by a real, unmocked configurator.

Discussion

Raised as a review comment on #5246. A fix was drafted there (a #pinnedDescriptors map plus an addConfig override redirecting same-name registrations back to the pinned descriptor) but reverted as too much bookkeeping for a single-PR fix, since this is a pre-existing, generic risk of the _pin mechanism rather than something specific to the telemetry mock.

Suggested direction

Fix this once, generically, in FrameworkMockConfigurator/_pin (or in ModulesConfigurator.addConfig's re-registration semantics) rather than per-module. Whatever shape it takes, add a regression test that calls a built-in module's real enableX helper against FrameworkMockConfigurator and asserts the pinned accessor still reflects the mock after initialization.