Rust 1.54.0 lints (#2483)

## Issue Addressed

N/A

## Proposed Changes

- Removing a bunch of unnecessary references
- Updated `Error::VariantError` to `Error::Variant`
- There were additional enum variant lints that I ignored, because I thought our variant names were fine
- removed `MonitoredValidator`'s `pubkey` field, because I couldn't find it used anywhere. It looks like we just use the string version of the pubkey (the `id` field) if there is no index

## Additional Info



Co-authored-by: realbigsean <seananderson33@gmail.com>

account_manager/src/wallet/recover.rs

@@ -71,7 +71,7 @@ pub fn cli_run(matches: &ArgMatches, wallet_base_dir: PathBuf) -> Result<(), Str
 
     let mnemonic = read_mnemonic_from_cli(mnemonic_path, stdin_inputs)?;
 
-    let wallet = create_wallet_from_mnemonic(matches, &wallet_base_dir.as_path(), &mnemonic)
+    let wallet = create_wallet_from_mnemonic(matches, wallet_base_dir.as_path(), &mnemonic)
         .map_err(|e| format!("Unable to create wallet: {:?}", e))?;
 
     println!("Your wallet has been successfully recovered.");