Fixes BigInt parsing losing precision in IntegerInput

[iPaulPro]

Description

When entering a large number into an IntegerInput component, it is parsed as a JSON string and loses precision.

For example, entering 85604566775863511922702956178915374775782418036268384638508224920020197708340 is parsed into 85604566775863516368369806302131844469805175632226226214501379502487210295296.

This is fixed by first attempting to convert the string value to a BigInt and then returning that value if successful.

Additional Information

• [x] I have read the contributing docs (if this is your first contribution)
• [x] This is not a duplicate of any existing pull request

Your ENS/address: paulburke.eth

[iPaulPro]

@technophile-04 Great catch and thanks for the incredibly fast merge!