feat: add serverRunning() API (v0.14) for progressive loading

[chagong]

Summary

Add serverRunning() promise to the ExtensionAPI (v0.14) that resolves when the language server process is alive and can handle requests, even before project imports complete. This enables dependent extensions (like vscode-java-dependency) to show progressive content during long imports instead of waiting for full initialization.

Changes

extension.api.ts

• Bumped extensionApiVersion to '0.14'
• Added readonly serverRunning?: () => Promise<boolean> to the API interface

apiManager.ts

• Added serverRunningPromiseResolve field
• Created serverRunningPromise and serverRunning async function in initialize()
• Added resolveServerRunningPromise() method

standardLanguageClient.ts

• Calls apiManager.resolveServerRunningPromise() at the top of the StatusNotification.type handler, before the switch statement

Context

This is part of a 3-repo change for progressive project loading:

1. eclipse-jdtls/eclipse.jdt.ls — Server-side progressive notifications
2. This PR — serverRunning() API (v0.14)
3. microsoft/vscode-java-dependency — Client-side progressive tree view rendering

API Difference

API	Resolves when
serverReady()	Server fully initialized (imports complete, build done)
serverRunning()	Server process alive, first status notification received

Extensions that want to show progressive content during import can await serverRunning() instead of serverReady().

[fbricon]

thanks @chagong!