Add Cancel major icon and deprecate mobile icon version

[anthonymenecola]

Feature request summary

• Add CancelMajor icon version for Cancel small equivalent
• Rename Cancel small to CancelMinor

Rationale

• Inconsistency in major/minor versions of the Cancel icon, as well as a legacy mobile-only version

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[sarahill]

Figma branch with the update to the name is merged. Let me know when you're ready to merge in the PR and we'll publish the change in Figma. Also let me know if you need help with the PR :) Thank you!