feat: rewrite the nip-4e implementation (#1)

Make NIP-4e a core feature, not an optional feature.

Note:
- The UI is broken and needs to be updated in a separate PR.

Reviewed-on: #1

crates/chat_ui/Cargo.toml

@@ -9,8 +9,6 @@ state = { path = "../state" }
 ui = { path = "../ui" }
 theme = { path = "../theme" }
 common = { path = "../common" }
-account = { path = "../account" }
-encryption = { path = "../encryption" }
 person = { path = "../person" }
 chat = { path = "../chat" }
 settings = { path = "../settings" }