[yesod-test] quote character not matching in bodyContains

[eahlberg]

I noticed that bodyContains (probably bodyEquals as well, but haven't confirmed) fails when matching quotes ('), e.g.. bodyContains "O'Connor". A similar issue was described and fixed for htmlContain* in #1768.

However, fixing this by escaping the input string raises the same issue as described in #1784 but for bodyContains etc, namely that there's no way to match strings verbatim, which I think is a valid use case. Therefore, it might make sense to add functions which match strings verbatim in a similar manner, e.g. bodyContainsPreEscaped etc.

This is easily solved locally but the fact that htmlContain* escapes input by default which bodyContains does not is a bit confusing.