Permit paying oneself (#10337)

* Allow paying to oneself

* cargo fmt

* Permit pay-to-self in CLI

No test here because we're just removing an [untested] special case.

Fixes #10339

cli/src/cli.rs

@@ -1530,11 +1530,6 @@ fn process_transfer(
 ) -> ProcessResult {
     let from = config.signers[from];
 
-    check_unique_pubkeys(
-        (&from.pubkey(), "cli keypair".to_string()),
-        (to, "to".to_string()),
-    )?;
-
     let (recent_blockhash, fee_calculator) =
         blockhash_query.get_blockhash_and_fee_calculator(rpc_client)?;