Revert #4333: "Remove UptimeManager#IsConnected"

[JonathanOppenheimer]

Reverts #4333

[Copilot]

Pull Request Overview

This PR reverts a previous change that removed the UptimeManager#IsConnected method and replaced it with direct peer tracking. The revert restores the original uptime manager-based connection checking.

• Restores IsConnected method to the uptime manager interface and implementation
• Removes peer tracking functionality from the network layer
• Adds test coverage for the restored IsConnected method

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
vms/platformvm/service.go	Reverts to using uptimeManager.IsConnected() instead of direct peer tracking
vms/platformvm/network/network.go	Removes peers field and Peers() method from Network struct
snow/uptime/manager_test.go	Adds test cases for IsConnected method behavior
snow/uptime/manager.go	Adds IsConnected method to Tracker interface
network/p2p/network_test.go	Removes test for Peers.Has() method
network/p2p/network.go	Removes Has() method from Peers struct

Comments suppressed due to low confidence (1)

network/p2p/network.go:50

• The NewNetwork function signature has been changed to use variadic ConnectionHandler parameters, but the calling code in vms/platformvm/network/network.go is still trying to pass a peers parameter. This will cause a compilation error.

func NewNetwork(
	log logging.Logger,
	sender common.AppSender,
	registerer prometheus.Registerer,
	namespace string,
	connectionHandlers ...ConnectionHandler,
) (*Network, error) {

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}