Merge topic 'curl-tls-verify'

4e62bc943c ctest: Verify TLS server certificate by default
8e92ee34f6 file(DOWNLOAD/UPLOAD): Verify TLS server certificate by default
dcaea54898 cmCTestCurl: Clarify names and logic using optional<bool>
03d37ae3ff cmFileCommand: Clarify names and logic using optional<bool>

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !9843