refactor: Use the same mechanism for autogenerated component id

[guillaumevincent]

To make the code more consistent, I added a method getUniqueId that is used by all components that
need a unique id. I put this id in the defaultProps object. Add also some tests for util
file.

[patternfly-build]

PatternFly-React preview: https://830-pr-patternfly-react-patternfly.surge.sh

[coveralls]

Pull Request Test Coverage Report for Build 2866

• 5 of 5 (100.0%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.01%) to 81.262%

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Totals
Change from base Build 2861:	-0.01%
Covered Lines:	3463
Relevant Lines:	4018

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💛 - Coveralls

[jschuler]

Great PR! But we do need to initialize the unique id in the constructors. Or at least have some other way of assigning unique id to the component. Props get evaluated before the component instances are created so if you have multiple of the same components on the page they will all have the same id otherwise.

[dmiller9911]

this does not work. Default props are only instantiated once on when this variable , defaultProps is created. The id will need to be setup in a "constructor" or better as a class property

class Something extends React.Component {
  this.id = this.props.id || getUniqueId();
}

[dmiller9911]

might be nice to allow a prefix for this so that we can make the id's somewhat useful

getUniqueId(prefix = '') {
  return (
   `${prefix}-` + new Date().getTime() +
    Math.random()
      .toString(36)
      .slice(2)
  );
}

this would allow us to do something like getUniqueId('pf-switch') we could even add the pf- by default and have the preson just pass the component name to it.

[guillaumevincent]

@dmiller9911 and @jschuler done
Tell me if this implementation is good

[tlabaj]

Looks good! Could you just merge the merge conflicts. Thanks!

[tlabaj]

LGtM