Add APIs for available memory on eUICC.

Add new API flag. And add permissions check for:
READ_PHONE_STATE permission and
READ_PHONE_STATE_PRIVILEGED and carrier privilege.

Bug: 312793756
Test: m, atest EuiccServiceTest EuiccConnectorTest EuiccControllerTest EuiccManagerTest
Change-Id: I622ffb45cc3e98ee362b1406db936c7734d99f64
diff --git a/flags/uicc.aconfig b/flags/uicc.aconfig
index 5b74d1a..c1b860f 100644
--- a/flags/uicc.aconfig
+++ b/flags/uicc.aconfig
@@ -18,10 +18,15 @@
     description: "This flag controls the visibility of the getCarrierRestrictionStatus in carrierRestrictionRules class."
     bug:"313553044"
 }
-
 flag {
     name: "carrier_restriction_rules_enhancement"
     namespace: "telephony"
     description: "This flag controls the new enhancements to the existing carrier restrictions rules"
     bug:"317226653"
-}
\ No newline at end of file
+}
+flag {
+    name: "esim_available_memory"
+    namespace: "telephony"
+    description: "This flag controls eSIM available memory feature."
+    bug:"318348580"
+}