Use 24px icons only (+ small icon updates)

[thisisdano]

This PR updates a significant subset of our icons we mistakenly distributed as the 20px version instead of our standard 24px version. Notably, this improves the output of the login icon so now it's consistent with the logout icon.

⚠️ Affects layout: This could the alignment and look of some icons

Old

New

Additional changes

• It also adds the script we use to copy and rename the Material icons (config/rename-material-icons.sh)
• It moves some social icons into the proper directory
• Replaces thumb_down_off_alt with thumb_down_alt to be consistent with thumb_up icon
• Updates camping icon to be more conformant with guidance alignments
• ⚠️ Breaking: Removes remove_red_eye icon from usa-icons and sprite: Duplicate of visibility