Expose a way to let user get flow instance id 

**Current behavior:**
Today there is no way to get context data of flow instance id or flow name

**Expected behavior:**
We should expose a way to let the user get it by either 
1. $flow.FlowName
2. $flow.FlowInstanceId

**What is the motivation / use case for changing the behavior?**

**Additional information you deem important (e.g. I need this tomorrow):**
