Update Git Attributes for JSON syntax highlighting in *.graphite fi…

…les (GraphiteEditor#1752)

* Update Git Attributes for `*.graphite`

Adds syntax highlighting on GitHub and treats the files as generated/binary.

* Mark test Graphite files as *not* generated

.gitattributes

@@ -4,3 +4,7 @@
 # The `eol=lf` sets the conversion to an LF line ending
 # https://git-scm.com/docs/gitattributes
 * text=auto eol=lf
+
+# Adds syntax highlighting to Graphite files on GitHub and minimizes diffs both locally and on GitHub
+*.graphite binary linguist-generated linguist-language=JSON
+/node-graph/graphene-cli/test_files/*.graphite text diff -linguist-generated