android: fix deep-linking from web

Looks like custom-scheme links no longer work in all browsers. They do on
Firefox, but the don't in Chrome and other default browsers.

So, switch to intent links on Android:
https://developer.chrome.com/multidevice/android/intents

Example:
```
<a href="intent://meet.jit.si/test123#Intent;scheme=org.jitsi.meet;package=org.jitsi.meet;end">Open Jitsi Meet</a>
```

interface_config.js

     /**
      * Specify mobile app scheme for opening the app from the mobile browser.
      */
-    // APP_SCHEME: 'org.jitsi.meet'
+    // APP_SCHEME: 'org.jitsi.meet',
+
+    /**
+     * Specify the Android app package name.
+     */
+    // ANDROID_APP_PACKAGE: 'org.jitsi.meet'
 };
 
 /* eslint-enable no-unused-vars, no-var, max-len */

react/features/base/util/uri.js

  *
  * @type {string}
  */
-export const URI_PROTOCOL_PATTERN = '([a-z][a-z0-9\\.\\+-]*:)';
+export const URI_PROTOCOL_PATTERN = '^([a-z][a-z0-9\\.\\+-]*:)';
 
 /**
  * Excludes/removes certain characters from a specific room (name) which are
  * @returns {string}
  */
 function _fixURIStringScheme(uri: string) {
-    const regex = new RegExp(`^${URI_PROTOCOL_PATTERN}+`, 'gi');
+    const regex = new RegExp(`${URI_PROTOCOL_PATTERN}+`, 'gi');
     const match: Array<string> | null = regex.exec(uri);
 
     if (match) {
     str = str.replace(/\s/g, '');
 
     // protocol
-    regex = new RegExp(`^${URI_PROTOCOL_PATTERN}`, 'gi');
+    regex = new RegExp(URI_PROTOCOL_PATTERN, 'gi');
     match = regex.exec(str);
     if (match) {
         obj.protocol = match[1].toLowerCase();

react/features/deep-linking/components/DeepLinkingMobilePage.web.js

     t: Function
 };
 
-/**
- * The type of the React {@code Component} state of
- * {@link DeepLinkingMobilePage}.
- */
-type State = {
-
-    /**
-     * The URL to link to on the button for opening the mobile app.
-     */
-    joinURL: string
-};
-
 /**
  * React component representing mobile browser page.
  *
  * @class DeepLinkingMobilePage
  */
-class DeepLinkingMobilePage extends Component<Props, State> {
-    state = {
-        joinURL: ''
-    };
-
+class DeepLinkingMobilePage extends Component<Props> {
     /**
      * Initializes a new {@code DeepLinkingMobilePage} instance.
      *
     constructor(props: Props) {
         super(props);
 
-        this.state = {
-            joinURL: generateDeepLinkingURL()
-        };
-
         // Bind event handlers so they are only bound once per instance.
         this._onDownloadApp = this._onDownloadApp.bind(this);
         this._onOpenApp = this._onOpenApp.bind(this);
                     </a>
                     <a
                         className = { `${_SNS}__href` }
-                        href = { this.state.joinURL }
+                        href = { generateDeepLinkingURL() }
                         onClick = { this._onOpenApp }
                         rel = 'noopener noreferrer'
                         target = '_blank'>

react/features/deep-linking/functions.js

     // like to open the current URL in the mobile app. The only way to do it
     // appears to be a link with an app-specific scheme, not a Universal
     // Link.
+
     const appScheme = interfaceConfig.APP_SCHEME || 'org.jitsi.meet';
+    const { href } = window.location;
+    const regex = new RegExp(URI_PROTOCOL_PATTERN, 'gi');
+
+    // Android: use an intent link, custom schemes don't work in all browsers.
+    // https://developer.chrome.com/multidevice/android/intents
+    if (Platform.OS === 'android') {
+        // https://meet.jit.si/foo -> meet.jit.si/foo
+        const url = href.replace(regex, '').substr(3);
+        const pkg = interfaceConfig.ANDROID_APP_PACKAGE || 'org.jitsi.meet';
 
-    // Replace the protocol part with the app scheme.
+        return `intent://${url}/#Intent;scheme=${appScheme};package=${pkg};end`;
+    }
 
-    return window.location.href.replace(
-            new RegExp(`^${URI_PROTOCOL_PATTERN}`), `${appScheme}:`);
+    // iOS: Replace the protocol part with the app scheme.
+    return href.replace(regex, `${appScheme}:`);
 }
 
 /**