Automatic key import / export + Expected monad

Summary:
There are many things going on here (perhaps a bit much for a single patch):

- When an attachment is of mime type "application/pgp-keys", a button is added to import the key to GPG
- When sending a mail and crypto is enabled (encryption, signing or both), the public key of the first private key found is sent as an un-encrypted attachment (T6994)
- The `mailcrypto.{h,cpp}` was, for the most part, rewritten
- Introduction of the expected monad, inspired by what was proposed for C++ [here](https://isocpp.org/files/papers/n4015.pdf), but not at all a strict implementation of this specification. We may want to add some more features of this standard later.

The rationale for some of the choices:

- I found mailcrypto a bit hard to edit to add new features, and a great part was commented code to prepare for the support the SMIME crypto format, which would (in my current knowledge) not be used for sending emails.
- One thing I found that may be missing in the code base was a standardized way of handling errors in C++ code. Since exceptions are disabled I think that the functional way is the way to go. After some research I found the Expected monad / tagged union / sum type, which seemed to suit the problem particularly well.

In the long run, I hope we would move the entire code base to use `Expected` to indicate if a function might fail.

Of course every choice made here is to be considered as a proposition for doing things / RFC, critics wholeheartedly accepted.

Reviewers: cmollekopf

Tags: #kube

Maniphest Tasks: T6994, T8147, T6995

Differential Revision: https://phabricator.kde.org/D11158

1 files changed, 14 insertions, 1 deletions

diff --git a/tests/teststore.cpp b/tests/teststore.cpp
index 9d56dd33..84e2da20 100644
--- a/tests/teststore.cpp
+++ b/tests/teststore.cpp
@@ -64,6 +64,19 @@ static void createMail(const QVariantMap &object, const QByteArray &folder = {})
     auto ccAddresses = toStringList(object["cc"].toList());
     auto bccAddresses = toStringList(object["bcc"].toList());
 
+    QList<Attachment> attachments = {};
+    if (object.contains("attachments")) {
+        auto attachmentSpecs = object["attachments"].toList();
+        for (int i = 0; i < attachmentSpecs.size(); ++i) {
+            auto const &spec = attachmentSpecs.at(i).toMap();
+            attachments << Attachment{spec["name"].toString(),
+                spec["name"].toString(),
+                spec["mimeType"].toByteArray(),
+                false,
+                spec["data"].toByteArray()};
+        }
+    }
+
     KMime::Types::Mailbox mb;
     mb.fromUnicodeString("identity@example.org");
     auto msg = MailTemplates::createMessage({},
@@ -74,7 +87,7 @@ static void createMail(const QVariantMap &object, const QByteArray &folder = {})
             object["subject"].toString(),
             object["body"].toString(),
             object["bodyIsHtml"].toBool(),
-            {},
+            attachments,
             {},
             {});
     if (object.contains("messageId")) {