HPCC-10674 ECL support for writing JSON files

Test case will improve with the upcoming addition of reading json files.. as I can then read and output what has first been written.

Signed-off-by: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>
Perhaps.  I wasn't sure if what is stored in dfs may end up evolving once Atilla (and I) tackled the spraying bit.  I.e. perhaps spraying will require different file attributes?