Resolve "Language switch button not intuitive enough"

What does this MR do?

Replaces the language switcher with flags instead of the names

Screenshots

Before

After

Closes #252 (closed)

Does this MR meet the acceptance criteria?

• I have added tests to validate the new functionality.
• I have updated the documentation accordingly.
• I have added translations for all new client-side text.
• I have updated the changelog accordingly.