fix(state_share): new method to include credentials for state sharing (#500)

* fix(state_share): new method to include credentials for state sharing due to chrome introducing restrictions on setting protocols using the URL API

* cleaned up state url credential fix code

Author: chrisj

src/neuroglancer/datasource/state_share.ts

@@ -72,9 +72,9 @@ export class StateShare extends RefCounted { // call it a widget? no because it
               body: JSON.stringify(viewer.state.toJSON())
             }, responseJson)
           .then((res) => {
-            const stateUrl = new URL(res);
-            stateUrl.protocol = protocol; // copy protocol in case it contains authentication type
-            const link = `${window.location.origin}/#!${stateUrl}`;
+            const stateUrlProtcol = new URL(res).protocol;
+            const stateUrlWithoutProtocol = res.substring(stateUrlProtcol.length);
+            const link = `${window.location.origin}/#!${protocol}${stateUrlWithoutProtocol}`;
             navigator.clipboard.writeText(link).then(() => {
               StatusMessage.showTemporaryMessage('Share link copied to clipboard');
             });