refactor(workspace): decompose project into multiple crates

crates/core/src/lib.rs

@@ -0,0 +1,23 @@
+pub mod account;
+pub mod admin;
+pub mod autoconfig;
+pub mod cache;
+pub mod common;
+pub mod context;
+pub mod dashboard;
+pub mod database;
+pub mod envelope;
+pub mod error;
+pub mod imap;
+pub mod import;
+pub mod logger;
+pub mod mailbox;
+pub mod message;
+pub mod oauth2;
+pub mod settings;
+pub mod store;
+pub mod tasks;
+pub mod token;
+pub mod users;
+pub mod utils;
+pub mod version;