Refactor SignerSource to expose DerivationPath to other kinds of signers (#16933)

* One use statement

* Add stdin uri scheme

* Convert parse_signer_source to return Result

* A-Z deps

* Convert Usb data to Locator

* Pull DerivationPath out of Locator

* Wrap SignerSource to share derivation_path

* Review comments

* Check Filepath existence, readability in parse_signer_source

remote-wallet/src/remote_keypair.rs

@@ -1,7 +1,7 @@
 use {
     crate::{
         ledger::get_ledger_from_info,
-        locator::Manufacturer,
+        locator::{Locator, Manufacturer},
         remote_wallet::{
             RemoteWallet, RemoteWalletError, RemoteWalletInfo, RemoteWalletManager,
             RemoteWalletType,
@@ -56,12 +56,13 @@ impl Signer for RemoteKeypair {
 }
 
 pub fn generate_remote_keypair(
-    path: String,
+    locator: Locator,
+    derivation_path: DerivationPath,
     wallet_manager: &RemoteWalletManager,
     confirm_key: bool,
     keypair_name: &str,
 ) -> Result<RemoteKeypair, RemoteWalletError> {
-    let (remote_wallet_info, derivation_path) = RemoteWalletInfo::parse_path(path)?;
+    let remote_wallet_info = RemoteWalletInfo::parse_locator(locator);
     if remote_wallet_info.manufacturer == Manufacturer::Ledger {
         let ledger = get_ledger_from_info(remote_wallet_info, keypair_name, wallet_manager)?;
         let path = format!("{}{}", ledger.pretty_path, derivation_path.get_query());