Codebase: Finalize source code

[doerfli]

• Ensure correct license reference in source code (SPDX-License-Identifier: Apache-2.0)
• Use latest openzeppelin v5
• Set consistent solidity pragma (same as openzeppelin)
• Use latest solidity for building
• Codebase: Remove unused contracts #433
• Codebase: Remove commented code #432
• reorganize contracts directories #169
• Codebase: Cleanup Imports #431
• Function sort order #260
• Format source code