fix: Save msgs to key-contacts migration state and run migration periodically (#6956)

Save:
- (old contact id) -> (new contact id) mapping.
- The message id starting from which all messages are already migrated.
Run the migration from `housekeeping()` for at least 500 ms and for >= 1000 messages per run.

src/sql.rs

@@ -581,6 +581,12 @@ impl Sql {
         Ok(value)
     }
 
+    /// Removes the `key`'s value from the cache.
+    pub(crate) async fn uncache_raw_config(&self, key: &str) {
+        let mut lock = self.config_cache.write().await;
+        lock.remove(key);
+    }
+
     /// Sets configuration for the given key to 32-bit signed integer value.
     pub async fn set_raw_config_int(&self, key: &str, value: i32) -> Result<()> {
         self.set_raw_config(key, Some(&format!("{value}"))).await
@@ -724,6 +730,11 @@ pub async fn housekeeping(context: &Context) -> Result<()> {
         .context("Failed to cleanup HTTP cache")
         .log_err(context)
         .ok();
+    migrations::msgs_to_key_contacts(context)
+        .await
+        .context("migrations::msgs_to_key_contacts")
+        .log_err(context)
+        .ok();
 
     if let Err(err) = remove_unused_files(context).await {
         warn!(