fix: reject integers that do not fit the target type

[SashaMIT]

ToInt8E("128") returned -128 and a nil error. ToInt8E("-129") returned 127. ToUint8E("256") returned 0. ToInt8E(int64(128)) did the same. The string was parsed at the width of int, then cast to the narrower type, which keeps the low bits.

127 and -128 still fit in int8. 8.9 is still 8. 255 still fits in uint8.

Red: -128 and a nil error. Green: go test .

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}