feat: add migration part 1 banner (MESSENGER-7564)

bwi/Wellknown/Wellknown+Bwi.swift

@@ -94,6 +94,24 @@ public extension MXWellKnown {
         }
     }
     
+    @objc func migrationInfoLevel() -> Int {
+        do {
+            guard let bwiDict = self.jsonDictionary()["de.bwi"] as? [String : Any] else {
+                return 0
+            }
+            
+            let bwi = try WellknownBWI(dict: bwiDict)
+            if let migration = bwi.migrationBuMX {
+                return migration.level ?? 0
+            } else {
+              return 0
+            }
+        }
+        catch {
+            return 0
+        }
+    }
+    
     @objc func updateFederationStatus() {
         do {
             guard let bwiDict = self.jsonDictionary()["de.bwi"] as? [String : Any] else {

bwi/Wellknown/WellknownBWI.swift

@@ -21,6 +21,7 @@ struct WellknownBWI: Decodable {
     let dataPrivacyURL: String?
     let imprintURL: String?
     let federation: WellknownFederation?
+    let migrationBuMX: WellknownMigrationBuMX?
     
     init(dict: [String: Any]) throws {
         let jsonData = try JSONSerialization.data(withJSONObject: dict, options: [])
@@ -32,6 +33,7 @@ struct WellknownBWI: Decodable {
         case dataPrivacyURL = "data_privacy_url"
         case imprintURL = "imprint_url"
         case federation
+        case migrationBuMX = "migration_bumx"
     }
 }
 
@@ -52,3 +54,11 @@ struct WellknownFederation: Decodable {
     }
     
 }
+
+struct WellknownMigrationBuMX: Decodable {    
+    let level: Int?
+    
+    enum CodingKeys: String, CodingKey {
+        case level
+    }
+}