Trim whitespace from input in the username/email form field

What does this MR do?

Adds two jQuery functions that bind event listeners to inputs with class trim-whitespace or strip-whitespace.

Adds the class trim-whitespace to the username/email input form field for the web login (devise session new_base).

Why was this MR needed?

Closes #42637 (closed).

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• End-to-end tests pass (package-qa manual pipeline job)

What are the relevant issue numbers?

#42637 (closed)