SignerSource: rename input scheme to prompt, default to bip44 solana base key (#17154) (#17159)

* Rename ask to prompt

* Default to Solana bip44 base if no derivation-path

* Add SignerSource legacy field, support legacy ASK

* Update docs

* Fix docs: validator current doesn't support uri SignerSources

(cherry picked from commit a5ec3a0547)

Co-authored-by: Tyera Eulberg <teulberg@gmail.com>

docs/src/cli/conventions.md

@@ -48,13 +48,13 @@ on your wallet type.
 In a paper wallet, the keypair is securely derived from the seed words and
 optional passphrase you entered when the wallet was create. To use a paper
 wallet keypair anywhere the `<KEYPAIR>` text is shown in examples or help
-documents, enter the uri scheme `ask://` and the program will prompt you to
+documents, enter the uri scheme `prompt://` and the program will prompt you to
 enter your seed words when you run the command.
 
 To display the wallet address of a Paper Wallet:
 
 ```bash
-solana-keygen pubkey ask://
+solana-keygen pubkey prompt://
 ```
 
 #### File System Wallet