[browser] WasmRuntimeAssetsLocation is not always provided by WebAssembly SDK

[maraf]

Describe the bug

Avalonia browser assets rely on WasmRuntimeAssetsLocation in

Avalonia/src/Browser/Avalonia.Browser/build/Microsoft.AspNetCore.StaticWebAssets.props

Line 13 in a06ae34

<RelativePath>$(WasmRuntimeAssetsLocation)/%(FileName)%(Extension)</RelativePath>

. The property is not set if wasm-tools workload is not installed (WebAssembly SDK doesn't support it yet dotnet/runtime#90979).

Introduced in #14225
Reported by user in dotnet/runtime#109266

To Reproduce

dotnet new install avalonia.templates
dotnet new avalonia.xplat
dotnet publish *.Browser
dir *.Browser/bin/Release/net8.0-browser/publish/wwwroot/_framework/avalonia.js

Expected behavior

No response

Avalonia version

11.1.0

OS

No response

Additional context

No response

[kekekeks]

The property is not set if wasm-tools workload is not installed

Without wasm-tools the SDK won't re-link the mono runtime with SkiaSharp included, so it will be broken anyway.