Mint tx v1

[FabijanC]

Usage related changes

• Create txs with unique hashes when minting in non-lite mode
  • Close Check if POST /mint is using transaction version 0 #373

Development related changes

• Introduce and predeploy a ChargeableAccount that will hold a lot of funds and which will be charged for minting
• Refactor account utilities
  • Create starknet_devnet/account_util.py
  • Move existing testing utilities there and import them
  • Needed because starknet_devnet needed a way to sign txs
  • Extract balance setting logic to set_balance
• In a few places, replace decimal integer literals with hex (it's shorter and more common to see them as hex)

Checklist:

• Applied formatting - ./scripts/format.sh
• No linter errors - ./scripts/lint.sh
• Performed code self-review
• Rebased to the last commit of the target branch (or merged it into my branch)
• Documented the changes
• Linked the issues which this PR resolves
• Updated the tests
• All tests are passing