V4.4.0 release (firebase#659)

* Added FirebaseUiHandler for IAP integration and part of es6 migration

* - Added default button config for saml and oidc
- Readme file for firebaseuihandler
- Clarify localized binary generation for hyphenated language codes: `zh-TW`, `xh-CN`, `pt-PT`
- Added support for default tenant config key "*".

PiperOrigin-RevId: 284115536
Change-Id: I4c5a9c56cc4af05bc21fc05a058a6e6b839b9dc4

* fixed soy syntax

* added chagnelog for v4.4.0

* Do not remove the redirect status before redirecting to IdPs for immediate redirect flow

* Adds UX improvements to firebaseuihandler federated sign in redirect processing.

* Skip sign-in screen if email is prefilled.

* Added selectTenantUiHidden callback and do not trigger signInUiShown callback for immediate redirect.

* remove ie11 test

* update android test

Author: wti806

CHANGELOG.md

@@ -0,0 +1,3 @@
+* Added `FirebaseUiHandler` API to support [using external identities with Google Cloud IAP](https://github.com/firebase/firebaseui-web/blob/master/firebaseuihandler/README.md).
+* Added default configurations for `SAML` and `OIDC` providers.
+* Fixed the missing id attributes for input elements.

README.md

@@ -37,11 +37,12 @@ FirebaseUI.
 5. [Customization](#customizing-firebaseui-for-authentication)
 6. [Advanced](#advanced)
 7. [Developer Setup](#developer-setup)
-8. [Cordova Setup](#cordova-setup)
-9. [React DOM Setup](#react-dom-setup)
-10. [Angular Setup](#angular-setup)
-11. [Known issues](#known-issues)
-12. [Release Notes](#release-notes)
+8. [IAP External Identities Support with FirebaseUI](#iap-external-identities-support-with-firebaseui)
+9. [Cordova Setup](#cordova-setup)
+10. [React DOM Setup](#react-dom-setup)
+11. [Angular Setup](#angular-setup)
+12. [Known issues](#known-issues)
+13. [Release Notes](#release-notes)
 
 ## Demo
 
@@ -1687,6 +1688,13 @@ the other terminal that has the exported variables, run the tests:
 npm test -- --saucelabs --tunnelIdentifier=<the tunnel identifier>
 ```
 
+## IAP External Identities Support with FirebaseUI
+
+You can use FirebaseUI to build the authentication page to use external
+identities with
+[Google Cloud IAP](https://cloud.google.com/iap/docs/external-identities).
+The documentation can be found [here](firebaseuihandler/README.md).
+
 ## Cordova Setup
 
 ### Introduction