Don't crash if activateRichText was called before createActions

activateRichText emits textModeChanged signal, which leads to
richTextComposerActions::textModeChanged call. Which segfaults if table
actions are not yet created by explicit createActions call.
1 job for master in 7 minutes and 49 seconds (queued for 55 seconds)
Status Job ID Name Coverage
  Build
passed #48515
linux kf5-qt5 qt5.12

00:07:49

61.0%