feat: implement in memory store

1. the store works as a temporary store for connection data such as chats, messages & contacts
2. the store is primarily meant to illustrate the usage of the event emitter as a way to construct the state of the connection. This will likely be very inefficient to perform well at scale
3. the store is meant to be a quick way to have some visibility of data while testing
4. the store works for both legacy & MD connections

src/Store/index.ts

@@ -0,0 +1,2 @@
+import makeInMemoryStore from './make-in-memory-store'
+export { makeInMemoryStore }