Blazor WASM apps should default new runtime config options to link out unnecessary code

[eerhardt]

In order to support smaller applications, the following feature switches are being added to dotnet/runtime:

• System.Diagnostics.Tracing.EventSource.IsSupported
• System.Resources.UseSystemResourceKeys
• System.Diagnostics.Debugger.IsSupported
• System.Text.Encoding.EnableUnsafeUTF7Encoding
• System.Net.Http.EnableActivityPropagation

See the SDK support at dotnet/sdk#12362.

The Blazor SDK should default these new properties in order to get as small of app as possible.

<EventSourceSupport Condition="'$(EventSourceSupport)' == ''">false</EventSourceSupport>
<UseSystemResourceKeys Condition="'$(UseSystemResourceKeys)' == ''">true</UseSystemResourceKeys>
<EnableUnsafeUTF7Encoding Condition="'$(EnableUnsafeUTF7Encoding)' == ''">false</EnableUnsafeUTF7Encoding>

<RuntimeHostConfigurationOption Include="System.Net.Http.EnableActivityPropagation"
                                Value="false"
                                Trim="true" />

Note the Debugger.IsSupported is not implemented yet.

@pranavkm @SteveSandersonMS