Refactored Checkbox, TextAreaInput, WikiSelect, TextInput, CourseForm

[prathamVaidya]

What this PR does

Part of #5393 (Component refactor for React class components)

Changed Legacy Class Components to React functional components for all the components imported in course_form.jsx

Components Refactored:

• [x] checkbox.jsx
• [x] text_area_input.jsx
• [x] text_input.jsx
• [x] wiki_select.jsx

Also, moved string literals to i18n in course_form.jsx.

Screenshots

wiki_select.jsx : working ✅

text_input.jsx : working ✅

text_area.jsx : working ✅

checkbox.jsx was also working though not used anywhere. I imported and tested it separately.

[ragesoss]

I strongly prefer smaller PRs, especially for refactoring. One PR per component makes it much easier for me to review, as my eyes glaze over when reviewing many component refactors at once.