Create mechanism for static JSON export (KISS)

[timcosgrove]

Requirements

Next Build should be able to output static JSON data, so that applications that rely on that data continue to function under Next Build.

Acceptance criteria

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1. Next.js is able to query JSON:API, transform it appropriately for the expected output format, and output the data as JSON
2. A single KISS query is replicated in Next Build, and its output is effectively identical to the Content Build version
3. The Next Build-generated JSON is able to be consumed by its target application (local or Tugboat demonstration)
4. The existing workaround in next-build for vamc-ehr JSON data is removed.

Background & implementation details

In Content Build, static generation starts here: https://github.com/department-of-veterans-affairs/content-build/blob/main/src/site/stages/build/drupal/static-data-files/generate.js