Fix CMake return & update CMake messages

[zichguan-amd]

Motivation

Remove argument to return() in CMake. return does not take error code and will fail with CMP0140 enabled, it also does not terminate the file correctly under the old policy. Ref https://cmake.org/cmake/help/latest/command/return.html

Change "not building examples" message from STATUS to WARNING and make the preceding find_package quiet for better visibility.

Technical Details

Standardize CMake warning and status messages:

• Use WARNING for missing dependencies & unsupported ASICs for better visibility
• Use STATUS for unsupported platforms (CUDA/Windows/Linux)

Test Plan

rocJPEG is not properly skipped with return(1). With this PR it is properly skipped.

Test Result

Added/Updated documentation?

• Yes
• No, does not apply to this PR.

Included Visual Studio files?

• Yes
• No, does not apply to this PR.

Submission Checklist

• New examples contain proper CMake and Make files.
• I have updated relevant CI workflows and the new examples are being built and tested in CI.
• Check and guard against unsupported ASICs if relevant dependent libraries have limited support.
• Look over the contributing guidelines at https://github.com/ROCm/ROCm/blob/develop/CONTRIBUTING.md#pull-requests.