[clangd] Expand response files before CDB interpolation (#75753)

Summary:

After https://reviews.llvm.org/D143436 response files stopped working
with CDB interpolation. It has happened because interpolation removes
all unknown flags and extra input files. Response file is treated as an
extra input because it is not a flag. Moreover inference needs full
command line for driver mode and file type detection so all response
files have to be expanded for correct inference.

This patch partially reverts D143436 and add additional response file
expansion in OverlayCDB for CDBs pushed via LSP.

Test Plan: check-clangd

Tasks: https://github.com/llvm/llvm-project/issues/69690