Add support for cticks

[ahuang11]

Closes #5723

import numpy as np
import holoviews as hv

hv.extension("bokeh")

img = hv.Image(np.array([[0, 1], [2, 3]])).opts(
    cticks=[(1, "A"), (2, "B")], colorbar=True
)
img

Didn't implement for matplotlib because it already has cbar_ticks

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.48%. Comparing base (2ba3d78) to head (d72f80c).
Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6257      +/-   ##
==========================================
+ Coverage   88.39%   88.48%   +0.09%     
==========================================
  Files         323      323              
  Lines       67620    67687      +67     
==========================================
+ Hits        59770    59896     +126     
+ Misses       7850     7791      -59     

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