[Android] Inappbrowser cannot read specified fallback URL in intent scheme links

# Bug Report

## Problem
[Android] Inappbrowser cannot read specified fallback URL in intent scheme links

### What is expected to happen?
In inappbrowser, If the user click on external intent link with fallback URL (e.g.: 3rd party websites) and when an intent could not be resolved, or an external application could not be launched, then the user will be redirected to the fallback URL if it was given.

### What does actually happen?
If the user click on an intent link with fallback URL and when an intent could not be resolved, or an external application could not be launched, the inappbrowser cannot handle the fallback url and the webview generate the following error messagge:
Could not load because of net::ERR_UNKNOWN_URL_SCHEME

## Information

You may need the user to open external apps, so we need to handle this situation.
According to Google Chrome for Android (Android Intents with Chrome)
https://developer.chrome.com/docs/multidevice/android/intents/

The following information describe the problem:

A little known feature in Android lets you launch apps directly from a web page via an Android Intent. One scenario is launching an app when the user lands on a page, which you can achieve by embedding an iframe in the page with a custom URI-scheme set as the src, as follows: ` `. This works in the Chrome for Android browser, version 18 and earlier. It also works in the Android browser, of course.

The functionality has changed slightly in Chrome for Android, versions 25 and later. It is no longer possible to launch an Android app by setting an iframe's src attribute. For example, navigating an iframe to a URI with a custom scheme such as `paulsawesomeapp://` will not work even if the user has the appropriate app installed. Instead, you should implement a user gesture to launch the app via a custom scheme, or use the "intent:" syntax described in this article.

Syntax
The best practice is to construct an intent anchor and embed that into the page so the user can launch the app. This gives you a lot more flexibility in controlling how apps are launched, including the ability to pass extra information into the app via Intent Extras.

The basic syntax for an intent-based URI is as follows:

`intent:
HOST/URI-path // Optional host
#Intent;
package=\[string\];
action=\[string\];
category=\[string\];
component=\[string\];
scheme=\[string\];
end;`

Also, you may choose to specify fallback URL by adding the following string extra:

`S.browser_fallback_url=[encoded_full_url]`
When an intent could not be resolved, or an external application could not be launched, then the user will be redirected to the fallback URL if it was given.

Some example cases where Chrome does not launch an external application are as follows:

* The intent could not be resolved, i.e., no app can handle the intent.
* JavaScript timer tried to open an application without user gesture.

Note that `S.` is a way to define string extras. `S.browser_fallback_url` was chosen for backward compatibility, but the target app won't see `browser_fallback_url` value as Chrome removes it.

Examples
Here's an intent that launches the Zxing barcode scanner app. It follows the syntax thus:

`intent:
//scan/
#Intent;
package=com.google.zxing.client.android;
scheme=zxing;
end;`
To launch the Zxing barcode scanner app, you encode your href on the anchor as follows:

` Take a QR code `

Also, if fallback URL is specified, the full URL will look like this:

` Take a QR code `
Now the URL will get you to zxing.org if the app could not be found, or the link was triggered from JavaScript without user gesture (or for other cases where we don't launch an external application.)

Considerations #
If the activity you invoke via an intent contains extras, you can include these as well.

Only activities that have the category filter, android.intent.category.BROWSABLE are able to be invoked using this method as it indicates that the application is safe to open from the Browser.

### Command or Code

### Environment, Platform, Device

Android

### Version information

cordova-plugin-inappbrowser v5.0.0 and master
cordova-android v9.1.0 and master

## Checklist

- [x] I searched for existing GitHub issues
- [x] I updated all Cordova tooling to most recent version
- [x] I included all the necessary information above

Start by reproducing an unresolved Android intent link containing S.browser_fallback_url in the Cordova InAppBrowser, using the example intent syntax and fallback URL from the issue. Trace the Android intent-handling path and verify that an unresolved intent or failed external launch redirects the WebView to the specified fallback URL instead of returning ERR_UNKNOWN_URL_SCHEME.

Written by the indexing model from the issue text.