`require-computed-macros` auto fixes to deprecated code

[wagenet]

	filteredItems: computed('[email protected]', function() {
		return this.items.filterBy('isFiltered');
	}),

Becomes:

filteredItems: computed.filterBy('items', 'isFiltered'),

However, computed. properties are deprecated per https://deprecations.emberjs.com/v3.x#toc_deprecated-run-loop-and-computed-dot-access.

It should be:

import { filterBy } from '@ember/object/computed';

// SNIP

filteredItems: computed.filterBy('items', 'isFiltered'),

[bmish]

Yeah I agree we should avoid adding computed.. But going along with this fix, we'll ideally need to add the import statement for the specific macro if missing.

PR welcome.