`ciCompareLen(a, b, b.size()) == 0` expression is an equivalent of checking for
equality of `a` prefix with size `b.size()` with `b`.
`ciCompareLen(a, b, a.size()) == 0` is also the same thing but `a` is a prefix
`b` should start with.
With this PR we refactor `StringUtils::replaceAll` to accept `string_view` as suggested in a code comment. In addition, while we are touching this rebuild happy file, we slim it down a bit by moving a few sparingly used functions elsewhere.