Result status reason and result status icons are inconsistent

[rouke-broersma]

The result status icon does not change consistently.

When the result status reason is null there is no icon:

When the result status reason is empty string and the mutant status is survived the icon is 🕵️ and help text is 'Reason for Survived status':

When the result status reason is empty string and the mutant status is killed the icon is the same as for survived (🕵️) and help text is 'Reason for Killed status':

For static mutants with no result status reason it looks like the status icon is changed to 🗿 because it takes up the same space, but it is actually a completely different field.

This looks even weirder when the mutation testing tool has set the result status reason to empty string instead of null:

[hugo-vrijswijk]

Closed with #1620