feat: sign eip-712 message instead of hash

[banteg]

see also https://docs.safe.global/advanced/smart-account-signatures

What I did

sign eip-712 message instead of defunct message.

if you follow the naming in safe docs, i have switched eth_sign signature for ecdsa signature.

it has also allowed to remove the method to adjust v of the signature.

fixes: #54

How I did it

replace signing of safe_tx_hash with signing of safe_tx.

How to verify it

In [9]: yes.transfer(dev, '1 ether', nonce=1, sender=safe, submit=False)
Signing EIP712 Message
Domain
	Chain ID: 81457
	Contract: 0x...
Message
	to: 0x1a49351bdB4BE48C0009b661765D01ed58E8C2d8
	value: 0
	data: b'\xa9\x05\x9c\xbb\...'
	operation: 0
	safeTxGas: 0
	baseGas: 0
	gasPrice: 0
	gasToken: 0x0000000000000000000000000000000000000000
	refundReceiver: 0x0000000000000000000000000000000000000000
	nonce: 1


Sign:  [y/N]: y

Checklist

• Passes all linting checks (pre-commit and CI jobs)
• New test cases have been added and are passing
• Documentation has been updated
• PR title follows Conventional Commit standard (will be automatically included in the changelog)

[banteg]

some tests fail with GS026: Invalid owner provided
https://github.com/safe-global/safe-smart-account/blob/main/docs/error_codes.md

i tested in prod and it worked for me.