net: Add tests for failure on string parameters with embedded NUL characters
Summary:
Add tests to make sure lookup methods fail on std::string parameters with embedded NUL characters
This is a backport of Core PR17754 [2/3]
https://github.com/bitcoin/bitcoin/pull/17754/commits/fefb9165f23fe9d10ad092ec31715f906e0d2ee7
Depends on D8684
Test Plan: ninja && ninja check
Reviewers: #bitcoin_abc, Fabien, majcosta
Reviewed By: #bitcoin_abc, Fabien, majcosta
Differential Revision: https://reviews.bitcoinabc.org/D8685