Ensure linenoise can be safely used from multiple threads (#16388)

This addresses a data race for `linenoise::lnstate` and
`StdInOutConsole::_isPromptShowing` which could result in openrct2
crashing and misreporting values when inspected in debugger.

src/openrct2/interface/InteractiveConsole.h

@@ -12,6 +12,7 @@
 #include "../common.h"
 #include "../localisation/FormatCodes.h"
 
+#include <atomic>
 #include <future>
 #include <queue>
 #include <string>
@@ -53,7 +54,7 @@ class StdInOutConsole final : public InteractiveConsole
 {
 private:
     std::queue<std::tuple<std::promise<void>, std::string>> _evalQueue;
-    bool _isPromptShowing{};
+    std::atomic<bool> _isPromptShowing{};
 
 public:
     void Start();

src/thirdparty/linenoise.hpp

@@ -157,6 +157,7 @@
 #include <functional>
 #include <vector>
 #include <iostream>
+#include <mutex>
 
 namespace linenoise {
 
@@ -1094,6 +1095,7 @@ struct linenoiseState {
     int history_index;  /* The history index we are currently editing. */
 };
 
+static std::mutex lnstate_mutex;
 static struct linenoiseState lnstate;
 
 enum KEY_ACTION {
@@ -2092,6 +2094,7 @@ inline void linenoiseEditDeletePrevWord(struct linenoiseState *l) {
 
 inline void linenoiseEditRefreshLine()
 {
+    std::lock_guard lock(lnstate_mutex);
     refreshLine(&lnstate);
 }
 
@@ -2105,6 +2108,7 @@ inline void linenoiseEditRefreshLine()
  * The function returns the length of the current buffer. */
 inline int linenoiseEdit(int stdin_fd, int stdout_fd, char *buf, int buflen, const char *prompt)
 {
+    std::lock_guard lock(lnstate_mutex);
     auto& l = lnstate;
 
     /* Populate the linenoise state that we pass to functions implementing