Use r_str_escape_utf8_for_json() for pfj z

[kazarmy]

No description provided.

[codecov-io]

Codecov Report

Merging #13734 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master   #13734      +/-   ##
==========================================
- Coverage   37.03%   37.03%   -0.01%     
==========================================
  Files         940      940              
  Lines      301172   301172              
==========================================
- Hits       111531   111528       -3     
- Misses     189641   189644       +3

Impacted Files	Coverage Δ
libr/util/format.c	66.62% <100%> (ø)	⬆️
libr/core/project.c	56.72% <0%> (-0.35%)	⬇️
libr/util/file.c	43.77% <0%> (-0.19%)	⬇️

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