[Pre7] HotReload for WebAssembly

[maraf]

Since we migrated to a more general purpose HotReload for WebAssembly in dotnet/sdk#49800, there is a change in when HotReload is available.

There is a new MSBuild property WasmEnableHotReload that is true by default when Configuration == "Debug". It be explicitly set to true to enable WebAssembly HotReload for other configurations.

HotReload for WebAssembly now consists of several pieces

• WasmEnableHotReload=true to include HotReload dll in build output
• dotnet watch (or VS alternative - F5) to enable the server part that watch over source files
• aspnet-browser-refresh.js script to glue server part and .NET runtime on WebAssembly together

HotReload is now available for other non-Blazor WebAssembly scenarios as well, for example using the wasmbrowser template