crypto: add tz4 to aggregate PK,PKH types

[emturner]

No description provided.

[rafoo]

Thanks for doing this, this will be useful in Michelson-in-Rust.

[rafoo]

As a sanity check, I've compared the values being tested with Octez:

$ alias mockup-client
alias mockup-client='octez-client --mode mockup --base-dir /tmp/mockup'
$ mockup-client create mockup
Base directory /tmp/mockup does not exist.
Create it with:
./octez-client --mode mockup --base-dir /tmp/mockup create mockup
Some commands (e.g., transfer) might not work correctly.
No protocol specified: using Alpha as default protocol.
Created mockup client base dir in /tmp/mockup
Tezos address added: tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx
Tezos address added: tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN
Tezos address added: tz1faswCTDciRzE4oJ9jn2Vm2dvjeyA9fUzU
Tezos address added: tz1b7tUupMgCNw2cCLpKTkSD1NZzB5TkP2sv
Tezos address added: tz1ddb9NMYHZi5UzPdzTZMYQQZoMub195zgv
$ mockup-client import secret key alice unencrypted:BLsk2wHXLW6gN9sbEN2rU84mmCSNZKn9KRKrw74LwHqEaLGwL3qQ31
Tezos address added: tz4DWZXsrP3bdPaZ5B3M3iLVoRMAyxw9oKLH
$ mockup-client show address alice
Hash: tz4DWZXsrP3bdPaZ5B3M3iLVoRMAyxw9oKLH
Public Key: BLpk1yE462s3cPX5t2HhvGPg3HSEUgqLi9q9Knwx7mbN4VuhEsvBYFvEz5Eu9shR7vZRY1k5PCtV
$ mockup-client normalize data '"BLpk1yE462s3cPX5t2HhvGPg3HSEUgqLi9q9Knwx7mbN4VuhEsvBYFvEz5Eu9shR7vZRY1k5PCtV"' of type key --unparsing-mode Optimized
0x03b46a862ef09f7f994c3d3570464dd8ab39305161e27b144ef900fc57e92c9429878b81af9678478d63f2eb36b01b2418
$ mockup-client check that bytes 0x68656c6c6f2c20626c73 were signed by alice to produce BLsig9WknWnGmPcJw1q9oCBr53UyjAWxxYNS5wz5HBKmCcuxCfK1Hwhs92YDFocvxUhXfUosgcTuzAEuAAjKzjy7isNhU3o2e8snmZyo9E85oRudCpM1MNtkeAAYEkSXUPLKtRYa9yFwni
Signature check successful.

From the same private key, message and signature we indeed get the same public key (in both b58 and binary formats) and the signature check succeeds.

[rafoo]

LGTM