Override Mullvad password (#233)

Set "m" as per official documentation:

https://mullvad.net/en/help/installing-mullvad-iphone-and-ipad/

CHANGELOG.md

@@ -20,6 +20,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Oeck provider is available again to free users.
 - Randomic crashes on profile updates. [#229](https://github.com/passepartoutvpn/passepartout-apple/pull/229)
+- Mullvad: enforce password to avoid "Auth failed". [#233](https://github.com/passepartoutvpn/passepartout-apple/pull/233)
 
 ## 2.0.0 (2022-10-02)
 

PassepartoutLibrary/Sources/PassepartoutProfiles/Managers/ProfileManager+Keychain.swift

@@ -29,7 +29,7 @@ import PassepartoutCore
 import PassepartoutUtils
 
 extension ProfileManager {
-    public func savePassword(forProfile profile: Profile) {
+    public func savePassword(forProfile profile: Profile, newPassword: String? = nil) {
         guard !profile.isPlaceholder else {
             assertionFailure("Placeholder")
             return
@@ -37,7 +37,7 @@ extension ProfileManager {
         guard let keychainEntry = profile.keychainEntry else {
             return
         }
-        let password = profile.account.password
+        let password = newPassword ?? profile.account.password
         guard !password.isEmpty else {
             keychain.removePassword(
                 for: keychainEntry,

PassepartoutLibrary/Sources/PassepartoutVPN/Managers/VPNManager+Configuration.swift

@@ -56,8 +56,20 @@ extension VPNManager {
                 }
             }
             
+            // specific provider customizations
+            var newPassword: String?
+            if let providerName = profile.providerName {
+                switch providerName {
+                case .mullvad:
+                    newPassword = "m"
+                    
+                default:
+                    break
+                }
+            }
+            
             // IMPORTANT: must commit password to keychain (tunnel needs a password reference)
-            profileManager.savePassword(forProfile: profile)
+            profileManager.savePassword(forProfile: profile, newPassword: newPassword)
 
             let parameters = VPNConfigurationParameters(
                 profile,