Flower Integration V2

[yanchengnv]

Fixes # .

Description

This PR implements Flower Integration Version 2 to use Flower's new architecture.

In Flower's previous architecture, on the server side, there are two processes: the superlink process and the server-app process. Flare is responsible for starting and stopping both processes. On client side, the supernode and client-app are included into a single process, and Flare is responsible fro starting and stopping this process.

In the new Flower architecture, on the server side, there is a superlink process, and Flare is responsible for starting and stopping this process. Once started, Flare issues the "flwr run" command to the superlink to submit a Flower app. In the meanwhile, Flare issues the "flwr ls" command periodically to query the status of the submitted app until the app is finished. On the client side, there is one process called Supernode, and Flare is responsible for starting and stopping this process. Flare does not need to start the server-app or client-app processes - these will be managed by the Flower system.

The overall integration architecture remains the same. The only difference is how to start and stop Flower apps.

Types of changes

• Non-breaking change (fix or new feature that would not break existing functionality).
• Breaking change (fix or new feature that would cause existing functionality to change).
• New tests added to cover the changes.
• Quick tests passed locally by running ./runtest.sh.
• In-line docstrings updated.
• Documentation updated.

[yanchengnv]

/build

[YuanTingHsieh]

LGTM, added some comments

[yanchengnv]

/build

[YuanTingHsieh]

Thanks! LGTM

[yanchengnv]

/build

[YuanTingHsieh]

/build