Add home settings toggle featureflag for enablingTwoLineText

- Have shouldUseTwoLine() be decided with the home settings toggle value

bug:316027081
spec: https://www.figma.com/file/uMzPkNMZpb7EyfHDo8usIa/V-%E2%80%A2-Toast-Butter?type=design&node-id=405-384593&mode=design&t=UBkdeuNlAdRh2FGU-0
Test:
Video: https://drive.google.com/file/d/15VUhNVro2fiwv3SzMda1StiPb3PV1eMT/view?usp=sharing
before searchPreferenceScreen: https://screenshot.googleplex.com/3uqdMsZoGSBYb6c
after searchPreferenceScreen: https://drive.google.com/file/d/15dswiHRTnafyhgQA_tL2tRc7vHFWdHbZ/view?usp=sharing
before homeSettingsPage: https://screenshot.googleplex.com/7wsNevxGun2KCCB
after homeSettingsPage: https://drive.google.com/file/d/15m5bjEyewlNHI_h26aygHa7zrgZ5qDF6/view?usp=sharing
AppListSettingsPage: https://drive.google.com/file/d/15hl4ScHBOLgKv3M38HtatMxQw85pgl7t/view?usp=sharing
Flag: enableTwolineToggle DEVELOPMENT

Change-Id: I3ad133dd51dcb97e14ccded730e7737c5049261a
diff --git a/aconfig/launcher.aconfig b/aconfig/launcher.aconfig
index 6d899d9..06943fb 100644
--- a/aconfig/launcher.aconfig
+++ b/aconfig/launcher.aconfig
@@ -16,6 +16,13 @@
 }
 
 flag {
+    name: "enable_twoline_toggle"
+    namespace: "launcher"
+    description: "Enables visibility in home settings to see the toggle to turn on/off two lines in all apps."
+    bug: "316027081"
+}
+
+flag {
     name: "enable_grid_only_overview"
     namespace: "launcher"
     description: "Enable a grid-only overview without a focused task."