clangd does not use flags provided through hard_compiler_wrapper.py

[carpikes]

With the latest orchestra, the flags provided through hard_compiler_wrapper.py are passed directly to the compiler and they are not written in compile_commands.json, which is used by clangd to provide code completion.

At the moment, the only flag which is causing problems with ui/cold-revng is -fstdlib=libc++ which would be useful to write in some way in the compile_commands file.

[aleclearmind]

We need a custom .clangd file sadly.
We should automate what's decribed here.