Implement request for user data erasure

This adds UI for MSC4025 to the account deactivation dialog, if the
server supports it. We also switch away from our
customDeactivateAccountJob to libQuotient's.

Fixes #670.

src/neochatconnection.h

@@ -87,6 +87,11 @@ class NeoChatConnection : public Quotient::Connection
      */
     Q_PROPERTY(bool canCheckMutualRooms READ canCheckMutualRooms NOTIFY canCheckMutualRoomsChanged)
 
+    /**
+     * @brief Whether the server supports erasing user data when deactivating the account. This checks for MSC4025.
+     */
+    Q_PROPERTY(bool canEraseData READ canEraseData NOTIFY canEraseDataChanged)
+
 public:
     /**
      * @brief Defines the status after an attempt to change the password on an account.
@@ -104,6 +109,7 @@ public:
     Q_INVOKABLE void logout(bool serverSideLogout);
     Q_INVOKABLE QVariantList getSupportedRoomVersions() const;
     bool canCheckMutualRooms() const;
+    bool canEraseData() const;
 
     /**
      * @brief Change the password for an account.
@@ -123,7 +129,7 @@ public:
     [[nodiscard]] QString label() const;
     void setLabel(const QString &label);
 
-    Q_INVOKABLE void deactivateAccount(const QString &password);
+    Q_INVOKABLE void deactivateAccount(const QString &password, bool erase);
 
     ThreePIdModel *threePIdModel() const;
 
@@ -194,6 +200,7 @@ Q_SIGNALS:
     void userConsentRequired(QUrl url);
     void badgeNotificationCountChanged(NeoChatConnection *connection, int count);
     void canCheckMutualRoomsChanged();
+    void canEraseDataChanged();
 
     /**
      * @brief Request a message be shown to the user of the given type.
@@ -223,4 +230,5 @@ private:
     QCache<QUrl, LinkPreviewer> m_linkPreviewers;
 
     bool m_canCheckMutualRooms = false;
+    bool m_canEraseData = false;
 };