Add Alt Text for Images

[Mephistic]

Problem

For accessibility, all images should have an appropriate alt text. That is not currently the case on our site - we should add appropriate (I18n-compliant) alt text to all images.

Success Criteria

• All images on site have alt text
• Set up linting rule to force Images to have an alt text specified (see https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/main/docs/rules/alt-text.md)

Related Links

• A11Y Linter for alt text: https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/main/docs/rules/alt-text.md
• Examples of A11y page audits for this rule (courtesy of Konstantin):
  • https://docs.google.com/document/d/1kqfKmfG-tutdsEvQU2tB8xKNXgM0508n8jww0skJu9I/edit
  • https://docs.google.com/document/d/1xBbDDkHIo1RvU4EouyiJeQEwZrHFs2r-TB6N5KbMKZM/edit?usp=sharing
  • https://docs.google.com/document/d/1NEkonYj-Ee7AXIrzlBhM8k0EBc2OmN8qG7Ga48lRrKc/edit