[FEATURE] Sync and get messages

[NADEE-MJ]

Is your feature request related to a problem? Please describe. Sync with server to update all rooms and messages/get users current state and also ability to get messages from a single room, including older messages.

Describe the solution you'd like

• [x] store messages locally on device probably in json format
• [x] sync to get current user information, store next_batch for next sync call
• [x] get messages for a single room, get older messages in batches.

Additional context Matrix Client-Server API

[NADEE-MJ]

Here are the changes I have made in the initial commit:

1. added sync and messages commands in main.dart. It is probably not a good place but is good for testing.
2. Fixed requester class: getRequest can now send requests with data, uses params in the link instead of passing them into the http client like the other methods in the class
3. added sync and getNewMessages to the user class, still a work in progress, but they are both currently are working however the data is not going anywhere.
4. simplified UserInfo class and moved some functionality into a JsonFileHandler class, also added some new attributes to store info for syncing and getting messages.
5. Added MessageUpdate and MessageInfo to store new messages received from sync and getNewMessages api calls.

[NADEE-MJ]

solved with pr #19, all features from this issue have been added and I am now closing the issue, still need to write tests for it. That is the next major step we need to take.

We also need to start using test-driven development so that we can find errors before we make them.