Refactor SenderFileDataAdapter structure in uniffi module

- Removed `pub(crate)` visibility from the `SenderFileDataAdapter` struct and its `inner` field to streamline access control.
- This change simplifies the interface while maintaining encapsulation, contributing to a cleaner codebase.

Signed-off-by: Pushkar Mishra <[email protected]>

Author: pushkarm029

drop-core/uniffi/src/sender.rs

@@ -47,8 +47,8 @@ pub trait SenderFileData: Send + Sync {
 
 /// Adapter that bridges this crate's `SenderFileData` trait to the
 /// `arkdropx_sender::SenderFileData` trait expected by the lower-level crate.
-pub(crate) struct SenderFileDataAdapter {
-    pub(crate) inner: Arc<dyn SenderFileData>,
+struct SenderFileDataAdapter {
+    inner: Arc<dyn SenderFileData>,
 }
 impl arkdropx_sender::SenderFileData for SenderFileDataAdapter {
     fn len(&self) -> u64 {