update api to comply with REST

add delete build endpoint
parse some info to new build view

frontend/lib/models/build.dart

@@ -1,12 +1,14 @@
 class Build {
   final int id;
   final String pkg_name;
+  final int pkg_id;
   final String version;
   final int status;
   final int? start_time, end_time;
 
   Build(
       {required this.id,
+      required this.pkg_id,
       required this.pkg_name,
       required this.version,
       required this.start_time,
@@ -16,6 +18,7 @@ class Build {
   factory Build.fromJson(Map<String, dynamic> json) {
     return Build(
       id: json["id"] as int,
+      pkg_id: json["pkg_id"] as int,
       status: json["status"] as int,
       start_time: json["start_time"] as int?,
       end_time: json["end_time"] as int?,