Replace smart reply boolean setting with key-value list

This patch replaces the recently introduced
Settings.Global.ENABLE_SMART_REPLIES_IN_NOTIFICATIONS boolean setting
with a new Settings.Global.SMART_REPLIES_IN_NOTIFICATIONS_FLAGS
key-value list.

Rationale: This will allow us to add and tweak smart reply parameters
without polluting the global settings namespace.

Bug: 67765414
Test: atest SmartReplyConstantsTest
Change-Id: I284bb6b31618a234c4772d16ad6190a713035f1b
diff --git a/core/tests/coretests/src/android/provider/SettingsBackupTest.java b/core/tests/coretests/src/android/provider/SettingsBackupTest.java
index 853a36d..5bb9abe 100644
--- a/core/tests/coretests/src/android/provider/SettingsBackupTest.java
+++ b/core/tests/coretests/src/android/provider/SettingsBackupTest.java
@@ -220,7 +220,7 @@
                     Settings.Global.ENABLE_DELETION_HELPER_NO_THRESHOLD_TOGGLE,
                     Settings.Global.ENABLE_DISKSTATS_LOGGING,
                     Settings.Global.ENABLE_EPHEMERAL_FEATURE,
-                    Settings.Global.ENABLE_SMART_REPLIES_IN_NOTIFICATIONS,
+                    Settings.Global.SMART_REPLIES_IN_NOTIFICATIONS_FLAGS,
                     Settings.Global.ENHANCED_4G_MODE_ENABLED,
                     Settings.Global.EPHEMERAL_COOKIE_MAX_SIZE_BYTES,
                     Settings.Global.ERROR_LOGCAT_PREFIX,