tools: build all.json by combining generated JSON

Notes:

1. Removed a number of root properties that did not seem relevant: source, desc, and introduced_in. There no longer is a source, and the other two are from the first include and do not reflect the entire API.

2. As with https://github.com/nodejs/node/issues/20100, the current "desc" properties sometimes contained in-page links, other times referenced another page, and often did not match the links in the original HTML or JSON file. I chose to standardize on external links as "desc" values are isolated snippets as opposed to all.html which can be viewed as a standalone and self contained document.

3. Eliminated preprocessing for @include entirely, including the test case for this function.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are updated
• commit message follows commit guidelines