SIP: Permissionless Package Introspection

[92GC]

Summary

Add native functions to sui::package for querying package identity and metadata:

public native fun current_package_id(): address;
public native fun policy_for(package_id: address): u8;
public native fun is_immutable(package_id: address): bool;
public native fun version_for(package_id: address): u64;

// Added for completeness don't have need
public native fun original_package_id(package_id: address): address;
public native fun dependency_package(
    package_id: address,
    dependency_original_id: address,
): Option<address>;

## Problem

These require protocol support—UpgradeCap access cannot solve them:
Sui would need to moves upgradecaos to a global table like was done did with coin metadatacaps, so object passing or access is not required.

[admin-aftermath]

Was anticipating writing a smaller SIP for the version_for function. Would simplify common package versioning pattern: replace const CURRENT_VERSION + Config.version + version check with a Config.min_acceptable_version + sui::package::version check. (I prefer version over version_for). No longer will you forget to update the const CURRENT_VERSION on a package upgrade.

I can see the other functions being useful in their own ways too. All in all, simple SIP but has an immediate impact.