Support ESLint v8 by switching from ESLint's internal traverser to estraverse

[bmish]

Fixes #1332. A few rules did not work with ESLint v8 because it has been converted to ESM which disallows us from accessing ESLint's internal files including its traverser class.

Note: I had to rewrite one of the traversals in require-computed-property-dependencies because estraverse does not appear to support ClassProperty:

  ● require-computed-property-dependencies › invalid › 
        import { computed } from '@ember/object';
        class Test {
          @computed('firstName', {
            get() {
              return this.firstName + ' ' + this.lastName;
            },
            set(key, value) {}
          })
          fullName
        }
      

    Unknown node type ClassProperty.
    Occurred while linting <input>:2

      141 |   let importedInjectName;
      142 |
    > 143 |   Extraverse.traverse(node, {
          |              ^
      144 |     enter(child) {
      145 |       if (types.isImportDeclaration(child)) {
      146 |         if (child.source.value === 'ember') {

      at Controller.traverse (node_modules/estraverse/estraverse.js:465:31)