Enable QT_NO_KEYWORDS for all Qt using code in SMTK. The requires
replacing `slots:` with `Q_SLOTS:`, `signals:` with `Q_SIGNALS:`,
`emit` with `Q_EMIT`, and `foreach` with `Q_FOREACH`.

Enables QT_NO_KEYWORDS for plugins using `smtk_add_plugin`, which
will affect some external smtk modules.

Address MacOS wrapping errors with QT macros