Add getAuthTokensForCredStore method to Authorization aidl.

This is CL adds and implements getAuthTokensForCredStore.

Bug: 159341610
Test: CtsVerifier
Change-Id: I71eabc0932eae56a6396f867320461e12b257897
diff --git a/keystore2/src/database.rs b/keystore2/src/database.rs
index 57ca7aa..5f19cf0 100644
--- a/keystore2/src/database.rs
+++ b/keystore2/src/database.rs
@@ -738,6 +738,11 @@
         self.0
     }
 
+    /// Returns the value of MonotonicRawTime in milli seconds as i64
+    pub fn milli_seconds(&self) -> i64 {
+        self.0 * 1000
+    }
+
     /// Like i64::checked_sub.
     pub fn checked_sub(&self, other: &Self) -> Option<Self> {
         self.0.checked_sub(other.0).map(Self)
@@ -790,6 +795,11 @@
     pub fn time_received(&self) -> MonotonicRawTime {
         self.time_received
     }
+
+    /// Returns the challenge value of the auth token.
+    pub fn challenge(&self) -> i64 {
+        self.auth_token.challenge
+    }
 }
 
 /// Shared in-memory databases get destroyed as soon as the last connection to them gets closed.