synchronous variant of jsonata

[mmkal]

Hi 👋

We're using jsonata to allow our customers to write custom matchers for the state of an object. As it stands right now, this means the place where we call jsonata(customerThing.expression).evaluate(ourData) we have to add await. Which means that function has to become async, and we ideally don't want that. We don't want to enable any custom functions, and certainly not async ones. So we'd prefer to have a synchronous version of jsonata. And looking at the code, I noticed that almost none of it needs to be asynchronous for any reason other than it might call some asynchronous user-defined function.

So, this PR uses a really dumb script to create a whole separate submodule of the package (under ./sync) which:

• uses regex to replace async and await with /* async */ and /* await */
• uses regex to replace Promise.all(...) with Array.from(...) (pointless calling Array.from on something that's already an array, but avoids complicated syntax modification
• replaces all if (isPromise(result)) { ... } with if (isPromise(result)) throw new Error('no promises pls')

It also copies over all tests, modifying them to use the sync version of jsonata instead:

• skips 4 tests + the async-function.js tests which are specifically for time-based and user-defined async function
• runs and passes all 1733 other tests(!)

Not sure if you'll want to accept and maintain this - the implementation right now is a hack. But it seems pretty valuable to provide an API that doesn't require calling from an async function. So, opening a PR if for no other reason than as a PSA - it can be used right now, at least from node, by adding "jsonata": "github:mmkal/jsonata#syncify.js" to package.json.

Note: a library like quansync might be a good option for supporting both sync and async without having to duplicate the code.