sdk: prefer direct use of RefreshToken ctor instead of implicit `#[…

…from]` conversions

This might be controversial, but I do strongly prefer explicit over
implicit, in this case: it helps looking at the use cases, when using
the LSP's goto_references().

crates/matrix-sdk/src/client/futures.rs

@@ -153,15 +153,15 @@ where
                                     // need to sign out.
                                 }
                             };
-                            return Err(refresh_error.into());
+                            return Err(HttpError::RefreshToken(refresh_error));
                         }
 
                         _ => {
                             trace!("Token refresh: Token refresh failed.");
                             // This isn't necessarily correct, but matches the behaviour when
                             // implementing OIDC.
                             client.broadcast_unknown_token(soft_logout);
-                            return Err(refresh_error.into());
+                            return Err(HttpError::RefreshToken(refresh_error));
                         }
                     }
                 } else {

crates/matrix-sdk/src/error.rs

@@ -102,7 +102,7 @@ pub enum HttpError {
 
     /// An error occurred while refreshing the access token.
     #[error(transparent)]
-    RefreshToken(#[from] RefreshTokenError),
+    RefreshToken(RefreshTokenError),
 }
 
 #[rustfmt::skip] // stop rustfmt breaking the `<code>` in docs across multiple lines