Shopify CLI 4.0: SemVer, auto-updates, removing deprecated flags and commands

Shopify CLI 4.0 is released with three major changes: adoption of semantic versioning (SemVer) for clearer release communication, automatic self-upgrades via the installed package manager (skipped in CI and for major versions), and removal of the deprecated --force flag from app deploy/release commands in favor of granular --allow-updates and --allow-deletes flags. Several other deprecated commands and flags have also been removed, including shopify webhook trigger, shopify theme serve, and shopify app generate schema.