CMake Updates

[blowekamp]

Remove CMake code for old versions.

Replace LINK_PRIVATE and LINK_PUBLIC with PRIVATE and PUBLIC respectfully.

PR Checklist

• No API changes were made (or the changes have been approved)
• No major design changes were made (or the changes have been approved)
• Added test (or behavior not changed)
• Updated API documentation (or API not changed)
• Added license to new files (if any)
• Added Python wrapping to new files (if any) as described in ITK Software Guide Section 9.5
• Added ITK examples for all new major features (if any)

Refer to the ITK Software Guide for
further development details if necessary.