bug(mac): double-click of .kmp file should open in Keyman Configuration

[sgschantz]

Describe the bug

double-click of .kmp file should open in Keyman Configuration and offer to install it

Keyman apps

• Keyman for Android
• Keyman for iPhone and iPad
• Keyman for Linux
• Keyman for macOS
• Keyman for Windows
• Keyman Developer
• KeymanWeb
• Other - give details at bottom of form

Keyman version

alpha 19