Introduce replacement for getting and setting thread name: (#4312)

* In namespace ripple, introduces get_name function that takes a
  std:🧵:native_handle_type and returns a std::string.
* In namespace ripple, introduces get_name function that takes a
  std::thread or std::jthread and returns a std::string.
* In namespace ripple::this_thread, introduces get_name function
  that takes no parameters and returns the name of the current
  thread as a std::string.
* In namespace ripple::this_thread, introduces set_name function
  that takes a std::string_view and sets the name of the current
  thread.
* Intended to replace the beast utilities setCurrentThreadName
  and getCurrentThreadName.

src/test/basics/ThreadName_test.cpp

@@ -17,15 +17,13 @@
 */
 //==============================================================================
 
-#include <ripple/beast/core/CurrentThreadName.h>
+#include <ripple/basics/ThreadUtilities.h>
 #include <ripple/beast/unit_test.h>
-#include <atomic>
-#include <thread>
 
 namespace ripple {
 namespace test {
 
-class CurrentThreadName_test : public beast::unit_test::suite
+class ThreadName_test : public beast::unit_test::suite
 {
 private:
     static void
@@ -34,26 +32,19 @@ private:
         std::atomic<bool>* stop,
         std::atomic<int>* state)
     {
-        // Verify that upon creation a thread has no name.
-        auto const initialThreadName = beast::getCurrentThreadName();
-
         // Set the new name.
-        beast::setCurrentThreadName(myName);
+        this_thread::set_name(myName);
 
         // Indicate to caller that the name is set.
         *state = 1;
 
-        // If there is an initial thread name then we failed.
-        if (!initialThreadName.empty())
-            return;
-
         // Wait until all threads have their names.
         while (!*stop)
             ;
 
         // Make sure the thread name that we set before is still there
         // (not overwritten by, for instance, another thread).
-        if (beast::getCurrentThreadName() == myName)
+        if (this_thread::get_name() == myName)
             *state = 2;
     }
 
@@ -86,7 +77,7 @@ public:
     }
 };
 
-BEAST_DEFINE_TESTSUITE(CurrentThreadName, core, beast);
+BEAST_DEFINE_TESTSUITE(ThreadName, basics, ripple);
 
 }  // namespace test
 }  // namespace ripple

src/test/overlay/short_read_test.cpp

@@ -17,8 +17,8 @@
 */
 //==============================================================================
 
+#include <ripple/basics/ThreadUtilities.h>
 #include <ripple/basics/make_SSLContext.h>
-#include <ripple/beast/core/CurrentThreadName.h>
 #include <ripple/beast/unit_test.h>
 #include <test/jtx/envconfig.h>
 
@@ -630,7 +630,7 @@ public:
     short_read_test()
         : work_(io_context_.get_executor())
         , thread_(std::thread([this]() {
-            beast::setCurrentThreadName("io_context");
+            this_thread::set_name("io_context");
             this->io_context_.run();
         }))
         , context_(make_SSLContext(""))