[a11y] Show password is read, but cannot be accessed when creating an account

[sblatz]

Steps to reproduce

1. Turn Talkback or Voice Assistant on.
2. Go to Settings - Turn on Sync and create a new account.
3. Fill in a valid email account, a valid password and then repeat the password.
4. Tap on the "Show password" icon.

Expected behavior

The "Show password" icon is read and double-tapping on it is accessed and the user can see the password filled.

Actual behavior

The "Show password" icon is read even if it isn't highlighted, but double-tapping on it does nothing. The password is not displayed, the user cannot see it.

Device information

• Android device: Samsung Galaxy Tab S3 (Android 8)
• Fenix version: Beta 3.1.0-beta 3

┆Issue is synchronized with this Jira Bug
┆Issue Number: FXA-988

[vasilicatamas]

Verified this issue as fixed on FxA Prod 1.158.1 under Fenix Nightly (build #20500606) using a Samsung Galaxy Tab S3 (Android 8) and a Moto G6 (Android 9). The password is successfully revealed/hidden on double-tap.