refactor: rename method to avoid confusion

- rename SqliteDb::new to `_::open` as it's not return Self
lint message: methods called `new` usually return `Self`
help: for further information visit https://rust-lang.github.io/rust-clippy/rust-1.92.0/index.html#new_ret_no_self
- rename method `add` to `add_calgorithm`
The semantics of this has nothing to do with an `add` operation in the sense of the `Add` trait.
And method `add` can be confused for the standard trait method std::ops::Add::add
lint https://rust-lang.github.io/rust-clippy/rust-1.93.0/index.html#should_implement_trait

src/api/s3/copy.rs

@@ -545,7 +545,7 @@ pub async fn handle_upload_part_copy(
 
 	// Now, actually copy the blocks
 	let mut checksummer = Checksummer::init(&Default::default(), !dest_encryption.is_encrypted())
-		.add(dest_object_checksum_algorithm.map(|(algo, _)| algo));
+		.add_algorithm(dest_object_checksum_algorithm.map(|(algo, _)| algo));
 
 	// First, create a stream that is able to read the source blocks
 	// and extract the subrange if necessary.