api: Unencrypted group creation (#6927)

[iequidoo]

Let's discuss the naming here. At the Core level we don't need two separate APIs, so create_group_ex() or smth similar should work. The question is the naming in json-rpc (and CFFI if we decide to add it). Alternatives:

• create_email_group_chat() or just create_email_chat() (the word "chat" is needed to make it clear that a chat is created, not a message. Actually chat ID is returned). We don't use the word "email" for this purpose in the code currently, but maybe we want to switch to it. I'm not involved in the discussions a lot, so can't say much. But my "external" opinion is that technically everything is email and using this word only for a subset of chats/messages would complicate undestanding the code for newcomers and external audit. But if we switch to "email", probably we need to get rid of "adhoc" in the code.
• create_adhoc_{group,chat}(). We already have "adhoc" in receive_imf at least.

For now i named it create_group_chat_unencrypted() because i'm used to namespace/prefix naming personally and there are already Chat::is_encrypted() in Core and {FullChat,BasicChat}::is_encrypted in json-rpc which exactly reflect the difference between create_group_chat() and the new function and i decided not to introduce new words.

closes #6927

[link2xt]

We also need API to list email contacts. Otherwise there is no way to create anything other than a group with only self.
Maybe even a separate PR because it is useful by itself to modify existing adhoc groups.

[iequidoo]

We also need API to list email contacts. Otherwise there is no way to create anything other than a group with only self. Maybe even a separate PR because it is useful by itself to modify existing adhoc groups.

Done in #6958

[r10s]

the code lgtm as far as i can tell.

i tested the implementation already at deltachat/deltachat-ios#2770 - there are some screenshots - works like a charm.

thanks a lot!

[r10s]

for the api wording: from the angle that the core api serve the UI and an is very close to its needs and flows, create_email_chat() seems better

[adbenitez]

personally I like create_group_chat_unencrypted() because as said by @iequidoo it makes it easier to navigate the API since the same as create_group_chat() but with address-contacts, and corresponds better with the chat.is_encrypted() API but would also not die in a naming hill hehe

[iequidoo]

for the api wording: from the angle that the core api serve the UI and an is very close to its needs and flows, create_email_chat() seems better

I think that even in UIs the new feature should be named "New {plaintext,unencrypted} email" because it's for users who set up Delta Chat with their existing mailboxes and know that Delta Chat sends emails, so it should be clear how it's different from a "usual" encrypted email.

Let's wait for more opinions a bit and merge this.

[Hocuri]

I also like the API name create_group_chat_unencrypted(), for the reasons already stated. If I saw an API called create_email_chat(), I wouldn't know what it's doing - does it create a 1:1 chat or a group? If I knew DC less well, I might even wonder: Does it create a chat that uses email as the underlying transport?