Convert malloc + manual string building as appropriate to asprintf

[bob-beck]

Sweep the tree for patterns where strings are built by making an allocation and concatenating strings and other things together to a single asprintf call with appropriate error checking.

Ensure that in the case of string truncation that either an error ensues, or, that the truncated value is actually
safe.

[bob-beck]

A reminder if this gets unblocked, and you are pondering it because I put good first issue on it, If you put pr's up for this
you may assign me to review them. I will.