refactor: Replace Context::nosync flag with internal functions taking enum Sync (#4817)

src/context.rs

@@ -173,7 +173,6 @@ impl ContextBuilder {
 #[derive(Clone, Debug)]
 pub struct Context {
     pub(crate) inner: Arc<InnerContext>,
-    nosync: bool,
 }
 
 impl Deref for Context {
@@ -393,34 +392,11 @@ impl Context {
 
         let ctx = Context {
             inner: Arc::new(inner),
-            nosync: false,
         };
 
         Ok(ctx)
     }
 
-    /// Returns a `Context` in which sending sync messages must be skipped. `Self::unwrap_nosync()`
-    /// should be used to check this.
-    pub(crate) fn nosync(&self) -> Self {
-        Self {
-            inner: self.inner.clone(),
-            nosync: true,
-        }
-    }
-
-    /// Checks if sending sync messages must be skipped. Returns the original context and the result
-    /// of the check. If it's `true`, calls to [`Self::add_sync_item()`] mustn't be done to prevent
-    /// extra/recursive synchronisation.
-    pub(crate) fn unwrap_nosync(&self) -> (Self, bool) {
-        (
-            Self {
-                inner: self.inner.clone(),
-                nosync: false,
-            },
-            self.nosync,
-        )
-    }
-
     /// Starts the IO scheduler.
     pub async fn start_io(&mut self) {
         if !self.is_configured().await.unwrap_or_default() {