Use "Performance" instead of "Perf" in new Blazor WebAssembly diagnostics APIs and MSBuild properties

[danroth27]

Looks like we shortened "Performance" to "Perf" in several identifiers in the new Blazor WebAssembly diagnostics support:

• WasmPerfTracing MSBuild property
• WasmPerfInstrumentation MSBuild property
• collectPerfCounters JS API

The .NET naming guidelines say that we should avoid abbreviations in identifiers, so I think these should technically be updated from "Perf" to "Performance".