Add needsUserConnection function to check user connection status to shared extension utils package

[oskosk]

Introduces a new utility function needsUserConnection in the shared-extension-utils package. This function helps determine if a user connection is required based on two conditions:

1. The current user is not connected
2. The site is not a simple site

Proposed changes:

• Adds needsUserConnection function in needs-user-connection.js
• Imports and uses isCurrentUserConnected and isSimpleSite utility functions

Other information:

• [ ] Have you written new tests for your changes, if applicable?
• [ ] Have you checked the E2E test CI results, and verified that your changes do not break them?
• [ ] Have you tested your changes on WordPress.com, if applicable (if so, you'll see a generated comment below with a script to run)?

Jetpack product discussion

None, but see how we needed something like this again in https://github.com/Automattic/jetpack/pull/39064

Does this pull request change what data or activity we track or use?

No

Testing instructions:

• Go to '..'