feat(authenticator): Add support for TOTP to Authenticator

[mattcreaser]

• PR conforms to Pull Request guidelines.

Issue #, if available:

Description of changes:

• Merging the TOTP feature branch to main. This work has already been reviewing when merging to the feature branch.

This PR adds the following new string resources:

    <string name="amplify_ui_authenticator_button_copy_key">Copy Key</string>
    <string name="amplify_ui_authenticator_enter_totp_code">Please enter the code from your registered Authenticator app</string>
    <string name="amplify_ui_authenticator_step1_title">Step 1: Download an Authenticator App</string>
    <string name="amplify_ui_authenticator_step1_content">Authenticator apps generate one-time codes that can be used to verify your identity</string>
    <string name="amplify_ui_authenticator_step2_title">Step 2: Scan the QR code</string>
    <string name="amplify_ui_authenticator_step2_content">Open the Authenticator app and scan the QR code or enter the key to get your verification code</string>
    <string name="amplify_ui_authenticator_step3_title">Step 3: Verify your code</string>
    <string name="amplify_ui_authenticator_step3_content">Enter the 6 digit code from your Authenticator app</string>
    <string name="amplify_ui_authenticator_mfa_sms">Text Message (SMS)</string>
    <string name="amplify_ui_authenticator_mfa_totp">Authenticator App (TOTP)</string>
    <string name="amplify_ui_authenticator_title_signin_confirm_totp">Enter your one-time passcode</string>
    <string name="amplify_ui_authenticator_title_signin_continue_totp_setup">Enable Two-Factor Auth</string>
    <string name="amplify_ui_authenticator_title_signin_continue_mfa_select">Select your preferred Two-Factor Auth method</string>

How did you test these changes?
(Please add a line here how the changes were tested)

Documentation update required?

• No
• Yes (Please include a PR link for the documentation update) Doc update will be forthcoming.

General Checklist

• Added Unit Tests
• Added Integration Tests
• Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.