add bsdiff

src/main/java/com/mir4updater/backend/service/ApkInfoService.java

@@ -20,6 +20,10 @@ public class ApkInfoService {
         return apkInfoRepository.findApkInfosByPackageName(pkg);
     }
 
+    public ApkInfo getApkInfo(int id) {
+        return apkInfoRepository.findApkInfoByAppId(id);
+    }
+
     public List<ApkInfo> getAll() {
         return apkInfoRepository.findAll();
     }