Move to `yarn` to `npm`

[brandonlenz]

Context:

At one point in time, yarn was a net improvement over npm, so it was a good choice for this repository.

npm has made strides over the years where performance concerns are no longer a driver to remain on yarn

yarn versions and corresponding documentation feels disorganized

npm is the standard tool from which all others take inspiration, and therefore it is most guaranteed to retain "backwards" compatibility for consumers using other tools. Since the main focus of React USWDS is compatibility for adoption, npm is a logical choice.

yarn limitations have contributed to issues such as the Husky blockers for releases (#3155)

Acceptance criteria:

• React USWDS uses npm instead of yarn
• All yarn-specific scripts are replaced with npm equivalents
• Some dangerfile scripting depends on yarn specific output. It should be updated to use the npm equivalent