adjust flag definitions to upstream changes

Author: muhomorr

android/TerminalApp/java/com/android/system/virtualmachine/flags/Flags.kt

@@ -0,0 +1,6 @@
+package com.android.system.virtualmachine.flags;
+
+object Flags {
+    fun terminalGuiSupport(): Boolean = true
+    fun terminalStorageBalloon(): Boolean = false
+}

android/TerminalApp/java/com/android/virtualization/terminal/Flags.kt

@@ -35,6 +35,7 @@ import android.webkit.WebViewClient
 import android.widget.TextView
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
+import com.android.system.virtualmachine.flags.Flags
 import com.android.virtualization.terminal.CertificateUtils.createOrGetKey
 import com.android.virtualization.terminal.CertificateUtils.writeCertificateToFile
 import java.security.PrivateKey
@@ -218,7 +219,7 @@ class TerminalTabFragment() : Fragment() {
 
     private fun updateMainActivity() {
         val mainActivity = activity as MainActivity ?: return
-        if (terminalGuiSupport()) {
+        if (Flags.terminalGuiSupport()) {
             mainActivity.displayMenu!!.visibility = View.VISIBLE
             mainActivity.displayMenu!!.isEnabled = true
         }