File Input button size, stories update and small code refactors

[GomezIvann]

Checklist
(Check off all the items before submitting)

• Build process is done without errors and all tests pass in the /lib directory.
• Self-reviewed the code before submitting.
• Meets accessibility standards.
• Added/updated documentation to /website as needed.
• Added/updated tests as needed.

Description
Summary:

• Change File Input's button size to fitContent in file mode.
• Updated stories of the File Input component to try to solve chromatic snapshot testing issues regarding each file item's delete button states.
• Minor code refactors and styling improvements.
• Include localization for Delete file action aria-label and title.

Closes #1082 and #760