feat(metrics): add module rejection and fallback gauges

[JAdshead]

Description

added two additional holocron gauges.

1. to track the total number of rejected modules after each module map update.
2. to track the total number of modules which are using fallback externals.

Motivation and Context

Provide a high level metrics to indicate to users how unhealthy the state of their module map is.
Information on rejected modules and modules using externals information is already logged so this feature does not provide insight where there was none but exposes it in a different light.

How Has This Been Tested?

Locally started one-app with both modules which would be rejected and ones which load but required external fallbacks.

Types of Changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation (adding or updating documentation)
• Dependency update
• Security update

Checklist:

• My change requires a change to the documentation and I have updated the documentation accordingly.
• These changes should be applied to a maintenance branch.
• This change requires cross browser checks.
• Performance tests should be ran against the server prior to merging.
• This change impacts caching for client browsers.
• This change impacts HTTP headers.
• This change adds additional environment variable requirements for One App users.
• I have added the Apache 2.0 license header to any new files created.

What is the Impact to Developers Using One App?

[github-actions]

Size Change: 0 B

Total Size: 710 kB

ℹ️ View Unchanged

Filename	Size
./build/app/app.js	164 kB
./build/app/app~vendors.js	411 kB
./build/app/runtime.js	7.07 kB
./build/app/service-worker-client.js	7.25 kB
./build/app/vendors.js	121 kB

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[PixnBits]

three nitpicks, but one blocker(?) suggestion