refactor: refactor jQuery usages to element selectors

[srsgores]

Octane apps consuming this addon will throw the following error:

2vendor-e1f3e6c162fd0a87c91ac02da93f94a2.js:formatted:15812 Uncaught TypeError: (0 , a.jQuery) is not a function
at c.s.JQUERY_INTEGRATION.l.$ (vendor-e1f3e6c162fd0a87c91ac02da93f94a2.js:formatted:15812)
at c.didRender (vendor-e1f3e6c162fd0a87c91ac02da93f94a2.js:formatted:61007)
at c.trigger (vendor-e1f3e6c162fd0a87c91ac02da93f94a2.js:formatted:16196)
at c.r [as trigger] (vendor-e1f3e6c162fd0a87c91ac02da93f94a2.js:formatted:15197)
at n.i.didCreate (vendor-e1f3e6c162fd0a87c91ac02da93f94a2.js:formatted:5676)
at e.t.commit (vendor-e1f3e6c162fd0a87c91ac02da93f94a2.js:formatted:23477)
at e.r.commit (vendor-e1f3e6c162fd0a87c91ac02da93f94a2.js:formatted:23575)
at Be (vendor-e1f3e6c162fd0a87c91ac02da93f94a2.js:formatted:23681)
at r.i._renderRoots (vendor-e1f3e6c162fd0a87c91ac02da93f94a2.js:formatted:8235)
at r.i._renderRootsTransaction (vendor-e1f3e6c162fd0a87c91ac02da93f94a2.js:formatted:8257)

This PR removes the deprecated jQuery selectors in favour of "native", classic Ember selectors using this.element.

Later on, I plan on submitting another MR which migrates this addon to octane.

[lukemelia]

Looks good to me 👍

[lukemelia]

Thanks @srsgores!