qt_add_qml_module(): Reject invalid inputs

Example 1

As explained at https://doc.qt.io/qt-6/qtqml-modules-identifiedmodules.html , QML URIs cannot contain dashes/hypens. If we try to use "import My-Module", then

• qmlsc will produce a compilation error ("Main.qml:2:10: error: Expected token `;'")
• Uncompiled QML code will produce a runtime error with the same message

Example 2

C++ class names cannot contain dashes. "MyPlugin" is OK but "My-Plugin" is not.

However, qt6_add_qml_module() currently accepts these illegal inputs:

qt6_add_qml_module(My-Module
    URI My-Module # <-- Accepted by CMake, but generated module is not importable
    CLASS_NAME My-Plugin # <-- Accepted by CMake, but the generated C++ code is broken
    # ...
)

Suggestion
CMake should produce an error at configure-time if an invalid input is detected.