Make Icons / Emoji customizable

[IrrerPolterer]

Is your feature request related to a problem? Please describe.
The current use of icons/emoji can be confusing in places. The meaning of certain emoji is not always clear.

Describe the solution you'd like
I propose the possibility to customize all icons using the K9S configuration files.

Describe alternatives you've considered
The only viable alternative to avoid confusing icons is disabling icons using the k9s.ui.noIcons option in the configuration files. But this removes icons alltogether.

Additional context
One related discussion exists: #1860

[CodyKlimkofski]

A PR has been created for this here:
#2814

[imorte]

due to the inactivity of the previous author

see #3184