Allow specifying the number of bytes for fields added created using FrameV2::AddInteger()

[NoahAndrews]

It's very annoying that if I want to see an integer in hex mode using an analyzer that exports V2 frames, it's going to show every digit for all 8 bytes. If I have a lot of integer fields to look at, I might not even be able to fit all of them in my monitor unless I shrink the columns enough to cut off useful data in favor of useless zeros.

If analyzers had the ability to specify how many bytes the field has, hex mode can just show the leading zeros to match that number of bytes.