Update release notes link to preview5

Add MicroBuild signing to new WebView packages

Add support for XF.GridLength in attribute helpers

Clear event handler only if it's the current event handler value

Previously, when an event handler was reset it would unconditionally clear the event. Instead, it should check if the value that is attempted to be clear is actually the current value. If not (say, because it's stale), it's ignored. If it is, it's cleared.

Fixes #80

Remove unnecessary "@" from Razor files