[IndexedDB] Adhere better to the specification for idb object store related operations (#37682)

Many object store related operations require the transaction to be
checked: to ensure it is still active, and, if the operation is a write,
that the transaction is not read-only. I've added the
`check_transaction` method to perform these checks.

Additionally `Clear` was still half-implemented, so I went ahead and
implemented that.

---------

Signed-off-by: Ashwin Naren <arihant2math@gmail.com>

components/shared/net/indexeddb_thread.rs

@@ -92,6 +92,8 @@ pub enum AsyncReadWriteOperation {
     RemoveItem(
         IndexedDBKeyType, // Key
     ),
+    /// Clears all key/value pairs in the associated idb data
+    Clear,
 }
 
 /// Operations that are not executed instantly, but rather added to a