refactor: Replace global address lookup table cache with direct fetch approach

Replace the global AddressLookupTableCache with a direct fetch function to simplify address lookup table management. This change improves code maintainability by removing global state and makes the API more explicit.

Key changes:
- Remove AddressLookupTableCache and AddressLookupManager
- Add new fetch_address_lookup_table_account function
- Update TradeBuyParams and TradeSellParams to use AddressLookupTableAccount instead of Pubkey
- Update all examples to use the new direct fetch approach
- Update documentation to reflect the simplified workflow

README.md

@@ -150,7 +150,7 @@ let buy_params = sol_trade_sdk::TradeBuyParams {
   slippage_basis_points: slippage_basis_points,
   recent_blockhash: Some(recent_blockhash),
   extension_params: Box::new(params.clone()),
-  lookup_table_key: None,
+  address_lookup_table_account: None,
   wait_transaction_confirmed: true,
   create_input_token_ata: true,
   close_input_token_ata: true,