In anticipation of the next commit(s) adding threaded tests, we
need to ensure our lockorder checks work fine with multiple
threads. Sadly, currently we have tests in the form
`assert!(mutex.try_lock().is_ok())` to assert that a given mutex is
not locked by the caller to a function.
The fix is rather simple given we already track mutexes locked by a
thread in our `debug_sync` logic - simply replace the check with a
new extension trait which (for test builds) checks the locked state
by only looking at what was locked by the current thread.
On windows the symbol names appear to sometimes be truncated,
which causes the symbol name to not include the `::new` at the end.
This causes the regex to mis-match and track the wrong location
for the mutex construction, leading to bogus lockorder violations.
For example, in testing the following symbol name appeared on
Windows, without the function name itself:
`lightning::debug_sync::RwLock<std::collections:#️⃣:map::HashMap<lightning::chain::transaction::OutPoint,lightning::chain::chainmonitor::MonitorHolder<lightning::util::enforcing_trait_impls::EnforcingSigner>,std::collections:#️⃣:map::RandomState> >::`
