feat(scheduler): Decoupled Scheduler with Router and Adding Router Readiness Check

[christ-tt]

• Add a check that there's at least one ready pipeline, defined by all nodes in it are is_active, before dispatching requests.
• Decoupled router and scheduler; so we don't conditioning on strategy; and we let router handles the routing related tasks.

TODO

• Maybe rename node.is_active , as the active here means even after we have assigned layers / pipeline formation, node will need time for parameters loading, engine setup, cuda graph init, etc. The naming here may causing confusion for how we define active and standby for our nodes.

Current display info:

Feb 09 05:37:58.041 [scheduling] [DEBUG   ] scheduler.py:406          Allocation snapshot
Registered pipelines (2)
------------------------
Capacity: total=16 current capacity=0 per_pipeline={0: (8, 0), 1: (8, 0)}
  pipeline 0   | stages=2 | ready=False | cap=8 cur=8
    [00] 12D3KooWBcWf7v4kK9VT2dYh7N8mFvTo67BYeaeoAujxDJKyx8hd layers [  0,  18) | load   0/8   | latency    0.25 ms | active False
    [01] 12D3KooWC1nAdPXTsfQtYwNn28Vv61umqvdo8Edyzk4kUjnBnrYJ layers [ 18,  36) | load   0/8   | latency    0.25 ms | active False
  pipeline 1   | stages=2 | ready=False | cap=8 cur=8
    [00] 12D3KooWJmEVbSNJUF5U4jkan4BRXKT52f5sKzaNCwGer8UiCDJp layers [  0,  20) | load   0/8   | latency    0.25 ms | active False
    [01] 12D3KooWA4uVmdKSgDN6pmTxKTtaozqQZswYBUrjDoyP3LUkV2Bg layers [ 20,  36) | load   0/8   | latency    0.46 ms | active False

Standby nodes (0)
-----------------
  (none)