Clean up imports, formatting and tests.

Bug: n/a
Test: atest libapkverify.test libapkverify.integration_test
Change-Id: I39686d17927741297aa3feb02ed6043ee770933b
diff --git a/idsig/src/apksigv4.rs b/idsig/src/apksigv4.rs
index 6f4603d..5f4e92a 100644
--- a/idsig/src/apksigv4.rs
+++ b/idsig/src/apksigv4.rs
@@ -183,7 +183,7 @@
 
 #[cfg(test)]
 mod tests {
-    use crate::apksigv4::*;
+    use super::*;
     use std::io::Cursor;
 
     fn hexstring_from(s: &[u8]) -> String {