Change snapshots format to png

Summary:
There was an issue whereas snapshots were not properly rendered on retina devices.

After running a few tests, the issue seems to be solved by changing the snapshot format from jpeg to png.

Reviewed By: antonk52

Differential Revision: D41520939

fbshipit-source-id: 1563fe89162e41f71418357a7e58caaf46581f04

android/src/main/java/com/facebook/flipper/plugins/uidebugger/observers/TreeObserverManager.kt

@@ -115,7 +115,7 @@ class TreeObserverManager(val context: Context) {
     } else {
       val stream = ByteArrayOutputStream()
       val base64Stream = Base64OutputStream(stream, Base64.DEFAULT)
-      treeUpdate.snapshot.bitmap?.compress(Bitmap.CompressFormat.JPEG, 100, base64Stream)
+      treeUpdate.snapshot.bitmap?.compress(Bitmap.CompressFormat.PNG, 100, base64Stream)
       val snapshot = stream.toString()
       serialized =
           Json.encodeToString(