Adds REPORTER::HasMessageOfSeverity for WX_STRING_REPORTER,
which allows us to show simulation warnings and fail only if there's errors.
Also fixes a crash when SPICE_GENERATOR_KIBIS throws an IO_ERROR.
Fixes https://gitlab.com/kicad/code/kicad/-/issues/18143
Parenting dialogs to child windows of top level windows is most likely
not defined behavior. It's also likely that this behavior varies across
platforms so it' best not to risk doing it. wxWidgets does not check if
the dialog parent is actually a top level window. There may be other
places we are doing this with our message dialogs so we should do an
audit.
