M69: add FIS. (#5412)

* M69: add FIS.

* Bump FIS version to 1.2.0

FirebaseInstallations.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseInstallations'
-  s.version          = '1.1.1'
+  s.version          = '1.2.0'
   s.summary          = 'Firebase Installations'
 
   s.description      = <<-DESC

Releases/Manifests/6.23.0.json

@@ -7,6 +7,7 @@
   "FirebaseDatabase":"6.2.0",
   "FirebaseFirestore":"1.12.1",
   "FirebaseInAppMessaging":"0.19.3",
+  "FirebaseInstallations":"1.2.0",
   "FirebaseInstanceID":"4.3.4",
   "FirebaseMessaging":"4.3.1",
   "FirebaseStorage":"3.6.1",