fix(icon)!: remove getIconUrl for webpack's sake

[bennypowers]

What I did

1. remove the getIconUrl static method
2. add resolve static method
3. change the signature of addIconSet static method
4. Remove defaultIconSet static field

Testing Instructions

1.

Notes to Reviewers

1.

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: 69b21282e0b2c5fe37aab955b5b78cdc63b73359

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

| Name | Type | | -------------------- | ----- | | @patternfly/elements | Major |

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Click here if you're a maintainer who wants to add another changeset to this PR

[zeroedin]

Note for anyone reviewing. In order to bypass the jspm error, you can change the defaultProvider for the generator in /docs/_data/importMap.cjs to jsdelivr.

  const generator = new Generator({
    defaultProvider: 'jsdelivr',
    env: ['production', 'browser', 'module'],
  });

Doing so allowed me to test this branch.

[github-actions[bot]]

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