What would you like to be added:

This issue is the meta (epic) issue that links all issues related to adopting plugin architecture for PipeCD.

• Piped plugin architecture (v1.0 for piped) supports applications' deployments ref: Plugin architectured piped (pipedv1) supports deployment for applications #4980
• Make control plane support both piped v0 and v1 (plugin-arched piped) ref: Make PipeCD control plane support plugin-arched piped #5252
• Livestate feature in plugin architecture ref: Livestate feature in plugin architecture #5363
• Support stages as plugins [epic][plugin] Implement Stage Plugins #5367
• Migrate from pipedv0 -> pipedv1 [epic] Migration Tasks for Plugin-arched PipeCD #5542

Related issues:

• Remove deprecated features/codebase from pipedv1 Remove long time deprecated features from codebase (prepare for pipecd-v1 release) #5956

Why is this needed: