Migrate from GLEW to libepoxy or GLAD

Avogadro version: (please complete the following information from the About box):

• Avogadrolibs: master

Desktop version: (please complete the following information):

• OS: Fedora
• Version 42

Describe the bug Hi,

we are currently trying to get rid of GLEW in Fedora as it isn't maintained anymore. Also GLEW with the last release only supports GLX and not EGL.

There are two ways moving forward:

• Use libepoxy
• Use GLAD, or check out the webservice for glad2 to generate the files you need!

With both of them migration should be straight forward.

Thanks for considering!