[clang-tidy] Add `readability-use-rethrow` check

It would be useful to have a clang-tidy check that detects cases where code is clearly trying to rethrow the currently handled exception, but spells it as throw e; instead of throw;.

For example, code like this is easy to write:

try {
  f();
} catch (const std::exception &e) {
  log(e.what());
  throw e;
}

but if the intent is to rethrow the active exception, the clearer spelling is:

try {
  f();
} catch (const std::exception &e) {
  log(e.what());
  throw;
}

The latter expresses the intent directly and avoids the impression that the code is deliberately throwing the caught object as a new exception expression.