Implement Bip32 for seed-phrase/passphrase signing (#16942)

* Add Keypair helpers for bip32 derivation

* Plumb bip32 for SignerSourceKind::Ask

* Support full-path querystring

* Use as_ref

* Add public wrappers for from_uri cases

* Support master root derivations (and fix too-deep print

* Add ask:// HD documentation

* Update ASK elsewhere in docs

sdk/Cargo.toml

@@ -28,6 +28,7 @@ full = [
     "rand_chacha",
     "serde_json",
     "ed25519-dalek",
+    "ed25519-dalek-bip32",
     "solana-logger",
     "solana-crate-features",
     "libsecp256k1",
@@ -46,6 +47,7 @@ curve25519-dalek = { version = "2.1.0", optional = true }
 derivation-path = { version = "0.1.3", default-features = false }
 digest = { version = "0.9.0", optional = true }
 ed25519-dalek = { version = "=1.0.1", optional = true }
+ed25519-dalek-bip32 = { version = "0.1.1", optional = true }
 generic-array = { version = "0.14.3", default-features = false, features = ["serde", "more_lengths"], optional = true }
 hex = "0.4.2"
 hmac = "0.10.1"