chore: deduplicate builtin help action generation.

src/source/parser/platform_parsers/linux_parser.cpp

@@ -25,13 +25,7 @@ namespace argument_parser {
 				parsed_arguments.emplace_back(line);
 			}
 
-			add_argument({{flags::ShortArgument, "h"},
-						  {flags::LongArgument, "help"},
-						  {flags::Action, helpers::make_non_parametered_action([this]() {
-							   this->display_help(this->current_conventions());
-							   std::exit(0);
-						   })},
-						  {flags::HelpText, "Prints this help text."}});
+			prepare_help_flag();
 		}
 	} // namespace v2
 } // namespace argument_parser

src/source/parser/platform_parsers/macos_parser.cpp

@@ -25,13 +25,7 @@ namespace argument_parser {
 				}
 			}
 
-			add_argument({{flags::ShortArgument, "h"},
-						  {flags::LongArgument, "help"},
-						  {flags::Action, helpers::make_non_parametered_action([this]() {
-							   this->display_help(this->current_conventions());
-							   std::exit(0);
-						   })},
-						  {flags::HelpText, "Prints this help text."}});
+			prepare_help_flag();
 		}
 	} // namespace v2
 } // namespace argument_parser

src/source/parser/platform_parsers/windows_parser.cpp

@@ -3,7 +3,6 @@
 
 #include "windows_parser.hpp"
 #include "argument_parser.hpp"
-#include "parser_v2.hpp"
 
 #include <Windows.h>
 #include <iostream>
@@ -100,13 +99,7 @@ namespace argument_parser::v2 {
 		parse_windows_arguments(ref_parsed_args(),
 								[this](std::string const &program_name) { this->set_program_name(program_name); });
 
-		add_argument({{flags::ShortArgument, "h"},
-					  {flags::LongArgument, "help"},
-					  {flags::Action, helpers::make_non_parametered_action([this]() {
-						   this->display_help(this->current_conventions());
-						   std::exit(0);
-					   })},
-					  {flags::HelpText, "Prints this help text."}});
+		prepare_help_flag();
 	}
 } // namespace argument_parser::v2