EC721: Add isApprovedorOwner() support

[jaglinux]

isApprovedorOwner() is useful function which verifies given address is owner or approved for a nft.
Any reason why this function is not included ?

[jaglinux]

If there is interest, I can work on the PR to add the function and test cases.

[transmissions11]

thanks for opening an issue! i generally am not a fan of helper functions, tho this is one helper function that i think could be genuinely useful

if you'd like to open a PR against v7 that'd be great.

[jaglinux]

Sure.