hmp: Add 'one-insn-per-tb' command equivalent to 'singlestep'

The 'singlestep' HMP command is confusing, because it doesn't
actually have anything to do with single-stepping the CPU.  What it
does do is force TCG emulation to put one guest instruction in each
TB, which can be useful in some situations.

Create a new HMP command  'one-insn-per-tb', so we can document that
'singlestep' is just a deprecated synonym for it, and eventually
perhaps drop it.

We aren't obliged to do deprecate-and-drop for HMP commands,
but it's easy enough to do so, so we do.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20230417164041.684562-9-peter.maydell@linaro.org

softmmu/runstate-hmp-cmds.c

@@ -40,7 +40,7 @@ void hmp_info_status(Monitor *mon, const QDict *qdict)
     qapi_free_StatusInfo(info);
 }
 
-void hmp_singlestep(Monitor *mon, const QDict *qdict)
+void hmp_one_insn_per_tb(Monitor *mon, const QDict *qdict)
 {
     const char *option = qdict_get_try_str(qdict, "option");
     AccelState *accel = current_accel();