Perf opportunity, call RoGetActivationFactory much less often in xaml

[ChrisGuzak]

Describe the bug

I traced every RoGetActivationFactory being made when Xaml starts up and I see a lot of calls that can be avoided if the factories were cached like they are in cppwinrt.

    // When launching the  window and letting it paint, I observed
    // 206 calls to RoGetActivationFactory or RoGetClassObject
    // 68 unique names were passed.
    // If cached 138 (206-68) will be saved.
    // (206-68)/206 = ~67% calls will be cached.

I've got a drop-in replacement for the direct API use that implements caching and can share that with those interested in seeing what effect this has.

Steps to reproduce the bug

I used the VS debugger ability to trace on method calls, setting breakpoints on these APIs. and launching the bare bones WinUI App sample template.

observe redundant calls

Expected behavior

no redundancy, DRY.

Screenshots

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NuGet package version

None

Packaging type

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Windows version

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IDE

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Additional context

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