application: print command line

Somehow we've gotten away without printing the command line all this
time. In some contexts it is printed out by some other component but
we should print it out ourselves in Redpanda too.

Ref CORE-6746.

src/v/redpanda/application.cc

@@ -148,6 +148,7 @@
 #include <seastar/util/log.hh>
 
 #include <absl/log/globals.h>
+#include <fmt/format.h>
 #if __has_include(<google/protobuf/runtime_version.h>)
 #include <google/protobuf/runtime_version.h>
 #endif
@@ -430,8 +431,12 @@ int application::run(int ac, char** av) {
     // use endl for explicit flushing
     std::cout << community_msg << std::endl;
 
-    return app.run(ac, av, [this, &app] {
+    // NOLINTNEXTLINE: cppcoreguidelines-pro-bounds-pointer-arithmetic
+    std::string cmd_line = fmt::to_string(fmt::join(av, av + ac, " "));
+
+    return app.run(ac, av, [this, &app, cmd_line = std::move(cmd_line)] {
         vlog(_log.info, "Redpanda {}", redpanda_version());
+        vlog(_log.info, "Command line: {}", cmd_line);
         struct ::utsname buf;
         ::uname(&buf);
         vlog(