- Doxygen didn't generate documentation for a bunch of existing tools due to the absence of their directories in the doxygen configuration file. This patch adds all relevant directories to the appropriate list.
- clang-tools-extra/docs/Doxyfile seems to be unused and irrelevant, doxygen.cfg.in is passed to the CMake's Doxygen invocation, hence Doxyfile is removed.
The validity of proposed changes was manually checked by building doxygen-clang-tools and making sure that clangd and other tools are present in Doxygen-generated docs of clang-tools-extra