Add .prettierrc so it matches our existing code

This is so that people that are using prettier to
Auto format their code output code that matches
all of our existing code. It will not affect
Anyone that is not using prettier

Test plan:
* run prettier on a file, it should work

Change-Id: Ia396a5ab8953180f0b1b274d50190d0f943a2610
Reviewed-on: https://gerrit.instructure.com/131772
Reviewed-by: Dan Minkevitch <[email protected]>
Tested-by: Jenkins
Product-Review: Ryan Shaw <[email protected]>
QA-Review: Ryan Shaw <[email protected]>

.prettierrc

@@ -0,0 +1,6 @@
+{
+  "semi": false,
+  "printWidth": 100,
+  "singleQuote": true,
+  "bracketSpacing": false
+}