Kill dialog: vim navigation

[andys8]

Description

Add hjkl as navigation keys in kill dialog.

Issue

Closes #133

Type of change

Remove the irrelevant ones:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (if this change causes breakage or new behaviour, please state what):
• Other (something else - please specify if relevant):

Test methodology

Please state how this was tested:

The dialog

Please tick which platforms this change was tested on:

• Windows
• macOS
• Linux

Checklist

Please ensure all are ticked (and actually done):

• Change has been tested to work
• Areas your change affects have been linted using rustfmt
• Code has been self-reviewed
• Code has been tested and no new breakage is introduced unless intended
• Documentation has been added/updated if needed
• No merge conflicts arise from the change

Other information

Provide any other relevant information:

[ClementTsang]

@all-contributors add @andys8 for code

[allcontributors]

@ClementTsang

I've put up a pull request to add @andys8! 🎉