[Kernel] replace several @modify tags with @before

src/kernel_services/ast_queries/cil.mli

src/kernel_services/ast_queries/file.mli

...ernel_services/cmdline_parameters/parameter_customize.mli

src/kernel_services/plugin_entry_points/kernel.mli

src/kernel_services/plugin_entry_points/plugin.mli

src/libraries/stdlib/extlib.mli

src/libraries/utils/filepath.mli