bug(android/app): Install link does not work on keyman.com/amharic

[mcdurdin]

Describe the bug

Attempting to install the Keyman Amharic keyboard does not work from https://keyman.com/amharic or https://keyman-staging.com/amharic

To Reproduce

1. Go to either url above
2. Click on 'Download for Android'
3. Select 'Yes - Install Keyboard'
4. Keyman for Android opens, but no other action is performed

Expected behavior

Keyman for Android should start downloading the keyboard immediately.

I have not assessed whether this is an issue with the app or with the website. When resolving this, we should consider backwards compatibility with Keyman 10-13 as well.

---

Keyman for iPhone/iPad/Android:

• Device: Galaxy A90 5G
• OS: Android 10
• Keyman version: 14.0.219-beta

[darcywong00]

The external browser is downloading a link
keyman://localhost/open?keyboard=gff_amharic&language=am

From #2953 (comment)

We should never see keyman:download links in external browsers. So I'd be kinda keen to actually disable this so we don't end up doing things which break for people who haven't yet installed the app. Universal links are a much better long term solution.

Granted universal links aren't working. That PR disabled the keyman:// link from external browsers.

I could revert that... ❓

[darcywong00]

Recap from team discussion

Since the universal links didn't get fully implemented, we'll revert part of a0d1cb0
so that keyman:// links can be handled by external browsers too.

[darcywong00]

Fixed in 14.0 beta by #4292