Add a hint on u256 field

[stranger80]

Users keep struggling with providing input values to u256 fields in Remix plugin (Deploy and Invoke sections).
Add an '?' icon and when mouse hovers over it, display a 'tooltip' with an example input value.

[JorikSchellekens]

A better solution would be to integrate the form tool from prince https://www.npmjs.com/package/starknet-abi-forms

[rjnrohit]

Done! we are now in the middle of integrating starknet-abi-forms