CE-1863: add ce-ui-common dependency, and example

• Adds ce-ui-common as dependency
• Updates README and adds npmrc example file
• Swaps one small component with common component (ExternalLink, in the Help page) to demonstrate functionality (further work on that page will be done in a separate body of work)

Closes CE-1863

requested review from @alexandermadsen, @domonkosgulyas, @imretoth, and @simonrose

assigned to @christinajenks

How to review:

• can you install dependencies (npm ci) and run the project locally (npm start)?
• is the one example of using ce-ui-common (ExternalLink in Help page) functional as expected?
• sanity check no breaking changes (there shouldn't be any)

approved this merge request

Visual review of minor change: LGTM

mentioned in commit f078642a

merged