Ensure that msys2 bin dir is on PATH for bash

This should prepend the root directory of msys bin dir, on which the bash.exe
is located, as well as tools such as `printenv`.

Fixes conan-io#11986

conans/client/subsystems.py

@@ -61,6 +61,7 @@ def _windows_bash_wrapper(conanfile, command, env, envfiles_folder):
         _msystem = {"x86": "MINGW32"}.get(conanfile.settings.get_safe("arch"), "MINGW64")
         msys2_mode_env.define("MSYSTEM", _msystem)
         msys2_mode_env.define("MSYS2_PATH_TYPE", "inherit")
+        msys2_mode_env.prepend_path("PATH", os.path.dirname(shell_path))
         path = os.path.join(conanfile.generators_folder, "msys2_mode.bat")
         msys2_mode_env.vars(conanfile, "build").save_bat(path)
         env.append(path)