Fixes #83011

#83646 Webview: Cannot load resource outside of protocol root", if .md source is an network share (#84702)

* Check resource lower case strings when running on Windows

ElectronWebviewBasedWebview local resource roots are with uppercase authority (host name)

* Check lowercase resource availability if the resource is remote

* containsResource lowercase if root and resource are UNC

For #84602

For #77131

refs #84806

This reverts commit 122a598f.