fix(Table): Make IAction onClick optional

[Venefilyn]

What: Closes #3557

Additional issues:

[patternfly-build]

PatternFly-React preview: https://patternfly-react-pr-3558.surge.sh

[codecov-io]

Codecov Report

Merging #3558 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3558   +/-   ##
=======================================
  Coverage   67.11%   67.11%           
=======================================
  Files         903      903           
  Lines       25502    25502           
  Branches     2262     2262           
=======================================
  Hits        17115    17115           
  Misses       7346     7346           
  Partials     1041     1041

Flag	Coverage Δ
#misc	95.45% <ø> (ø)	⬆️
#patternfly3	69.29% <ø> (ø)	⬆️
#patternfly4	64.21% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
...rnfly-4/react-table/src/components/Table/Table.tsx	91.25% <ø> (ø)	⬆️

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[seanforyou23]

Looks like this fixes that console error we've had for a while Warning: Failed prop type: Invalid prop actions[1] supplied to Table. - nice work!!

[tlabaj]

LGTM