api!: jsonrpc: remove contacts from FullChat. To migrate load contacts on demand via get_contacts_by_ids using FullChat.contactIds (#7282)

closes #6945

### Why not deprecate it instead?
Because empty contact list is a more annoying-to-find bug in your app
than failing to build or getting undefined at runtime.

Also you would not see the deprecated hints anyway because for that you
need autogenerated types and those only exist for typescript currently.

deltachat-jsonrpc/src/api/types/chat.rs

@@ -10,7 +10,6 @@ use serde::{Deserialize, Serialize};
 use typescript_type_def::TypeDef;
 
 use super::color_int_to_hex_string;
-use super::contact::ContactObject;
 
 #[derive(Serialize, TypeDef, schemars::JsonSchema)]
 #[serde(rename_all = "camelCase")]
@@ -48,7 +47,6 @@ pub struct FullChat {
     chat_type: JsonrpcChatType,
     is_unpromoted: bool,
     is_self_talk: bool,
-    contacts: Vec<ContactObject>,
     contact_ids: Vec<u32>,
 
     /// Contact IDs of the past chat members.
@@ -83,20 +81,6 @@ impl FullChat {
         let contact_ids = get_chat_contacts(context, rust_chat_id).await?;
         let past_contact_ids = get_past_chat_contacts(context, rust_chat_id).await?;
 
-        let mut contacts = Vec::with_capacity(contact_ids.len());
-
-        for contact_id in &contact_ids {
-            contacts.push(
-                ContactObject::try_from_dc_contact(
-                    context,
-                    Contact::get_by_id(context, *contact_id)
-                        .await
-                        .context("failed to load contact")?,
-                )
-                .await?,
-            )
-        }
-
         let profile_image = match chat.get_profile_image(context).await? {
             Some(path_buf) => path_buf.to_str().map(|s| s.to_owned()),
             None => None,
@@ -132,7 +116,6 @@ impl FullChat {
             chat_type: chat.get_type().into(),
             is_unpromoted: chat.is_unpromoted(),
             is_self_talk: chat.is_self_talk(),
-            contacts,
             contact_ids: contact_ids.iter().map(|id| id.to_u32()).collect(),
             past_contact_ids: past_contact_ids.iter().map(|id| id.to_u32()).collect(),
             color,
@@ -150,7 +133,6 @@ impl FullChat {
 }
 
 /// cheaper version of fullchat, omits:
-/// - contacts
 /// - contact_ids
 /// - fresh_message_counter
 /// - ephemeral_timer