cs_log_set_filter() is removed in favor of cs_log_set_file_level() which
allows setting log verbosity of individual files and/or lines.
E.g.: `mg_=1,mjs=1,=4` - level for for everything except mjs and mongoose.
We use the fact that we are usually pretty careful with our file names and use prefixes consistently.
In mos, `debug.file_level` sets the option on boot and `Sys.SetDebug` is updated to parse `file_level` option to change it at runtime.
CL: Log file:line instead of function; add cs_log_set_file_level()
PUBLISHED_FROM=49f18d4d0d3dd224865129a4f8fe6cccd1d9bc12
Deomid Ryabkov