I added fixes to the existing checks of cppcoreguidelines-avoid-non-const-global-variables.
To fix the non-const_variable case, it utilizes QualType::addConst to make the non-const type constant.
For the indirection_to_non-const case, for the sake of simplicity of this check, the const keyword is simply inserted at the variable declaration's beginning. If someone knows a more elegant solution to this, I am happy to adapt it.
Thanks in advance for any feedback!