[counters] Disable register filter on valid_mask

This was previously used to not store counters that were not going to be dumped, but because we can now sample them, we have to make sure that they are stored, even if we do not plan to dump or sample them.
[proflog] Add counters to proflog type enumeration
[proflog] Add counters options parsing to proflog
[proflog] Add emit_string and emit_double utility functions
[proflog] Add counters functions

Two main functions :
 - counters_init : initalize the "counters" variable with all the counters registered durint the runtime initialization, called after runtime initialization
 - counters_sample : samples the counters values, called every "counters_interval" ms
[proflog] Add counters sampling to helper thread loop