added sm md and xl sizes for progress indicator

[Djfaucette]

Title of this pull request

• Link to discovery documentation (should contain all the planning and requirements for this work):
  • See the DISCOVERY.md template at the root of the project
• Link(s) to demo pages where this element can be viewed:

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What has changed and why

Summarize files edited as part of this MR along with a brief description of what was changed/why.

Testing instructions

Be sure to include detailed instructions on how your update can be tested by another developer.

Browser requirements

Your component should work in all of the following environments:

• Latest 2 versions of Edge
• Internet Explorer 11 (should be useable, not pixel perfect)
• Latest 2 versions of Firefox (one on Mac OS, one of Windows OS)
• Firefox 60.7.2 (or latest version for Red Hat Enterprise Linux distribution)
• Latest 2 versions of Chrome (one on Mac OS, one of Windows OS)
• Latest 2 versions of Safari
• Galaxy S9 Firefox
• iPhone X Safari
• iPad Pro Safari
• Pixel 3 Chrome

Your repository infrastructure updates should work for at least:

• Node v8.x
• NPM v7.x

Ready-for-merge Checklist

• Expected files: all files in this pull request are related to one feature request or issue (no stragglers)?
• Did browser testing pass?
• Did you update or add any necessary documentation (README.md, WHY.md, etc.)?
• Was this feature demo'd and the design review approved?
• Did you update the CHANGELOG.md file with a summary of this update?

Be sure to share your updates with the patternfly-elements-contribute@redhat.com mailing list!

[Djfaucette]

@castastrophe Should I be doing math on the pfe-vars to get different sizes?

[kylebuch8]

Leather Gloves Tease Mittens