Not possible to select recovery key

**Describe the bug**

When choosing a key file for recovery, the dialog shows the desired file
in the directory listing but doesn’t allow it to be selected.

In my case I transferred the file to ``/sdcard/Download/foo`` using adb.

hammerhead:/sdcard/Download $ file foo
foo: ASCII text

**To Reproduce**

1. Install clean element (from F-Droid in my case).
2. Launch and progress through config dialogs until it asks for the Recovery Key. Or go the „Verify this login“ menu and choose „Use a Recovery Passphrase or key“.
3. Tap “use file” button.
4. Navigate to directory where the keyfile is located, tap file.
5. Nothing happens; the file is not selected and the dialog remains open.

**Expected behavior**
Element should read the key from the file that is being tapped or at least
respond with an error message if the file couldn’t be read.

**Screenshots**


**Smartphone (please complete the following information):**
- Device: Nexus 5
- OS: LineageOS, Android version 9

**Additional context**
- App version and store v1.0.8 - F-Droid
- Homeserver: ``matrix.org``