Add "ignore whitespace" option

It would be nice to be able to easily disregard differences in whitespace (`\s`, `\t`, `\r`, `\n`, `\v`, `\f`, etc.) when comparing two JSON strings - something like the following option for the Unix/Linux `diff` utility:
```
       -b, --ignore-space-change
              ignore changes in the amount of white space
```
(from https://man7.org/linux/man-pages/man1/diff.1.html)