Adjusted hotkey assignments on Search / Replace and Find File dialogs.

[MKadaner]

Summary

Dialog default button does not need a hotkey. Most dialogs do not have hotkeys assigned to default buttons.

Checklist

• I have followed the contributing guidelines.
• I have discussed this with project maintainers: Editor Replace Button Hotkey #616, Editor Replace Button Hotkey #618
  
  If not checked, I accept that this work might be rejected in favor of a different grand plan.
  

Details

Also reassigned a few other hotkeys to make them more accessible.