Create JSON multi-sheet extractor plugin

[amarbakir]

Please explain how to summarize this PR for the Changelog:

• Initialize JSON multi-sheet extractor plugin
• Refactor out shared code from plugins/json-extractor into utils/extractor

Tell code reviewer how and what to test:

The plugins/json-extractor and plugins/json-multisheet-extractor plugins. Existing behavior has been kept

Requirements:

• Must allow users to upload a single JSON file which results in data correctly uploading to the corresponding sheets
• Should be able to determine sheet to data relationships through top level JSON keys. E.g.

{
	"contacts": [ // sheet 1
		{ // record 1
			"firstName": "John", // header 1, value
            		"lastName": "Doe", // header 2, value
            		"email": "john.doe@example.com"
		},
		{ // record 2
			"firstName": "Jane", // header 1, value
        			"lastName": "Smith",
        			"email": "jane.smith@example.com"
		},
	],
	"orders": [ // sheet 2
		{ // record 1
			"id": "ORD123456", // header 1, value
            		"amount": 250 // header 2, value
		},
	]
}

Resulting UI somewhat supports this, but a nice next step would be to allow for a multisheet import in one step through the UI, or at the very least not require one to go back to the files list to reimport the second sheet (load data from sheet contacts -> import data to contacts & load data from sheet order -> import data to order all in one step):

[amarbakir]

Btw this might be out of place but worth noting here since it's related to tesing/validating this effort

I'm pretty confident JSON extractor release 0.9.0 broke previous behavior. So if you have a working app using 0.8.2 and update to 0.9.0, the 0.9.0 JSON extractor doesn't work for both a valid, populated JSON array as well as an empty array (both cases are handled elegantly in 0.8.2). Both fail with this error

Event Received: file:created
TypeError: Cannot read properties of undefined (reading 'get')
    at Object.callback (/Users/amarbakir/dev/FlatfileApp/.flatfile/develop.js:96647:46)
    at exports.Client.trigger (/Users/amarbakir/dev/FlatfileApp/node_modules/@flatfile/listener/dist/index.cjs:1:6431)
    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
    at async exports.Client.dispatchEvent (/Users/amarbakir/dev/FlatfileApp/node_modules/@flatfile/listener/dist/index.cjs:1:6214)
    at async Object.message (/Users/amarbakir/dev/FlatfileApp/node_modules/@flatfile/listener-driver-pubsub/dist/index.js:108:17)

Given it was a minor version update, I would expect no breaking changes. Let me know if you'd like any further details on this or help debugging/fixing

[carlbrugger]

@amarbakir thanks for the PR! Will take a look.

On the @flatfile/plugins-json-extractor@0.9.0 issue, it should be resolved with @flatfile/util-extractor@2.2.1. Try deleting your node_modules and reinstalling.

[amarbakir]

@carlbrugger moving this over to #693

We will actually address the internal comments and AI bot comments before opening a PR back into this repo