CLI: dynamic signing reboot (#8384)

* Add keypair_util_from_path helper

* Cli: impl config.keypair as a trait object

* SDK: Add Debug and PartialEq for dyn Signer

* ClapUtils: Arg parsing from pubkey+signers to Presigner

* Impl Signers for &dyn Signer collections

* CLI: Add helper for getting signers from args

* CLI: Replace SigningAuthority with Signer trait-objs

* CLI: Drop disused signers command field

* CLI: Drop redundant tests

* Add clap validator that handles all current signer types

* clap_utils: Factor Presigner resolution to helper

* SDK: `From` for boxing Signer implementors to trait objects

* SDK: Derive `Clone` for `Presigner`

* Remove panic

* Cli: dedup signers in transfer for remote-wallet ergonomics

* Update docs vis-a-vis ASK changes

* Cli: update transaction types to use new dynamic-signer methods

* CLI: Fix tests No. 1

what to do about write_keypair outstanding

* Work around `CliConfig`'s signer not necessarily being a `Keypair`

* CLI: Fix tests No. 2

* Remove unused arg

* Remove unused methods

* Move offline arg constants upstream

* Make cli signing fallible

Co-authored-by: Trent Nelson <trent.a.b.nelson@gmail.com>

cli/tests/request_airdrop.rs

@@ -2,7 +2,6 @@ use solana_cli::cli::{process_command, CliCommand, CliConfig};
 use solana_client::rpc_client::RpcClient;
 use solana_core::validator::new_validator_for_tests;
 use solana_faucet::faucet::run_local_faucet;
-use solana_sdk::signature::Signer;
 use std::fs::remove_dir_all;
 use std::sync::mpsc::channel;