Eliminate all instances of SOS_DEFAULT_STRING_LEN

[cdwdirect]

Fixed-length strings and such strings stored in stack variables, even when carefully clamped and explicitly null-terminated, were a bad choice made in the early days of SOSflow implementation, before I knew better.

All SOS_DEFAULT_STRING_LEN instances should be removed from SOSflow. Strings should be unbounded in length, allocated, and memset to null, on the heap, period.

PROPOSED: Make simple wrapper functions...
char *SOS_string_copy(const char *);
void SOS_string_destroy(char *);
bool SOS_string_is_initalized(char **);
...OR...
// Create a std::string-style object for SOS, since SOS is written in C99.
SOS_string *name;
... so we have a single location where we can plug in various sanity checks, potential memory use optimizations like hashed-dupes with refcounts, and update the sosd_probe counts for memory usage related to strings.