chore: add merge driver (twilio-labs#991)

* create initial merge driver

* add test exit

* update random pixel to test

* update package.json

* test revert later

* work in progress merge driver

* more progress

* more commits to revert

* update mergePixels driver

* update scripts

* pick free pixel if conflict

* updates

* test: add tests for merge driver

* test: add tests for helpers

* update sync script

* improve error message

* update scirpt

* update script to merge properly

* update script

* explicitly pass uid

* pass common options

* pipe output of merge

* switch to inherit stdout

* modify stdio instead

* finish spinner

* stop and persist spinner before merging

* update merge driver configuration script

* make merge driver loud for testing

* update pixels

* update pixels for test

* update pixels

* create log file if merge conflict failed

* update pixels

* demo

* fix messaging and overriding file

* setup scripts

* remove --add flag from config

* reset pixels json

.gitattributes

@@ -0,0 +1 @@
+_data/pixels.json merge=pixels