Revert "FRAME: Create TransactionExtension as a replacement for SignedExtension (#2280)" (#3665)

This PR reverts #2280 which introduced `TransactionExtension` to replace
`SignedExtension`.

As a result of the discussion
[here](https://github.com/paritytech/polkadot-sdk/pull/3623#issuecomment-1986789700),
the changes will be reverted for now with plans to reintroduce the
concept in the future.

---------

Signed-off-by: georgepisaltu <george.pisaltu@parity.io>

substrate/client/network-gossip/src/state_machine.rs

@@ -550,8 +550,7 @@ mod tests {
 		NotificationSenderError, NotificationSenderT as NotificationSender, ReputationChange,
 	};
 	use sp_runtime::{
-		generic::UncheckedExtrinsic,
-		testing::{Block as RawBlock, MockCallU64, H256},
+		testing::{Block as RawBlock, ExtrinsicWrapper, H256},
 		traits::NumberFor,
 	};
 	use std::{
@@ -560,7 +559,7 @@ mod tests {
 		sync::{Arc, Mutex},
 	};
 
-	type Block = RawBlock<UncheckedExtrinsic<u64, MockCallU64, (), ()>>;
+	type Block = RawBlock<ExtrinsicWrapper<u64>>;
 
 	macro_rules! push_msg {
 		($consensus:expr, $topic:expr, $hash: expr, $m:expr) => {