Delay load RoMetadata, XmlLite, userenv dlls in WindowsAppRuntime

[Hemantxk]

In a WinUI3 packaged app created from the Visual Studio template, during the auto-initializer phase of WindowsAppRuntime, statically imported DLLs are loaded into memory by default. It is observed that WindowsAppRuntime doesn't call into rometadata.dll, xmllite.dll, and userenv.dll in this phase, but statically imports them. This change delay-loads these three DLLs so they are only loaded when actually needed.

Details

Below is what WindowsAppRuntime uses each of these DLLs for:

• RoMetadata - WindowsAppRuntime calls into MetaDataGetDispenser in WinRTGetMetadataFile, but it is not called for a WinUI3 packaged app.
• XmlLite - Used in WinAppSDK to read a package's AppxManifest, but this was not observed being called in a sample launch path. XmlLite can also get loaded by the MUX DLL if someone passes XAML in a string in code-behind (e.g., XamlReader), but this is not a common way to write XAML.
• userenv - WinAppSDK calls into this DLL for DeriveAppContainerSidFromAppContainerName. This was also not called in the launch path of an app. Browsing through the WinAppSDK code, it is called in GetSecurityDescriptorForAppContainerNames, and not all apps may need it.

Changes

• dev/WindowsAppRuntime_DLL/WindowsAppRuntime_DLL.vcxproj: Added rometadata.dll, xmllite.dll, and userenv.dll to the linker setting across all build configurations.

[Hemantxk]

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