Fix eslint issues

[rajakvk]

Fix eslint issues in the files merged along with PR #774

Files:

1. app/adapters/application.js Fix linting error (#775) #776
2. app/components/api-index-filter.js Fix linting error (#775) #777
3. app/components/api-index.js Fix linting error (#775) #777
4. app/components/class-field-description.js Fix linting error (#775) #778
5. app/components/ember-anchor.js Fix linting error (#775) #779
6. app/components/search-input/dropdown.js Fix linting error (#775) #781
7. app/controllers/method.js Fix linting error #775 #782
8. app/controllers/project-version.js Fix linting errors #775 #783
9. app/services/algolia.js Fix linting error #775 #784
10. tests/unit/services/head-data-test.js Fix prettier error #775 #785