Modernizing Cmake files based on the output of gr_modtool

I modernized the CMake files using the following method

1. `gr_modtool newmod display` to create a new project
2. Copy over all `CMakeLists.txt` and `.cmake` files from the new project
3. Re-add sources to `CMakeLists.txt` files

This fixes the issue on OSX where `_display_swig.so` would have hardcoded links to all libraries except for `libgnuradio-display.dylib`.