feat: extend the contract verification page to support Standard JSON Input

[vasyl-ivanchuk]

🌟 Feature Request

Extend the contract verification page to support Standard JSON Input.

📝 Description

Currently, in order to verify a contract - you need to use a set of input fields to specify all compiler settings. For some contracts, not all settings may be supported by the UI, making it impossible to verify them through the interface.

The page could support two modes (with a toggle or smth similar) to switch between the current input-based UI and a single input field for the full Standard JSON Input.

🤔 Rationale

• it will simplify things for users who already have the Standard JSON Input for verification. While they can use a direct API call, there have been requests asking why this isn't possible through the UI.

• when compiler settings are not supported by the UI, users can switch to another mode to provide the full Standard JSON Input.