[test_lib] Emit the line number of the test invocation

Parameterized tests share the same test name.  In order to distinguish
them in the test log, emit the line number of the `execute_test!` macro
invocation.

Signed-off-by: Chris Frantz <cfrantz@google.com>

sw/host/opentitanlib/src/test_utils/mod.rs

diff --git a/sw/host/opentitanlib/src/test_utils/mod.rs b/sw/host/opentitanlib/src/test_utils/mod.rs
index c07ddf6..4193343 100644
--- a/sw/host/opentitanlib/src/test_utils/mod.rs
+++ b/sw/host/opentitanlib/src/test_utils/mod.rs
@@ -38,9 +38,9 @@
 #[macro_export]
 macro_rules! execute_test {
     ($test:path, $($args:tt)*) => {
-        println!("Starting test {}...", stringify!($test));
+        println!("{}:Starting test {}...", line!(), stringify!($test));
         let result = $test($($args)*);
-        println!("Finished test {}: {:?}", stringify!($test), result);
+        println!("{}:Finished test {}: {:?}", line!(), stringify!($test), result);
         let _ = result?;
     };
 }