Resharding Workflow Status Updates

[PrismaPhonic]

We need the following status updates pulled from the new Workflow Show command:

1. Status indicating which shards are actively serving (MasterIsServing field from Workflow Show return)

• example: servingShards: -80,80-

2. Status showing whether we are Copying or Running for a given workflow.

• example: workflowState: Copying

3. Status boolean field to indicate whether we have gone above or below an acceptable max vreplication lag to allow for switching writes. As of now that acceptable value is 10s. We could allow configuring this value in the future, but for v1, let's just stick to this hard coded value.

• example: replicationLagUnsafe: true

Blockers

Item 3 is currently blocked until this PR is merged: vitessio/vitess#6635