feature/add-cache-and-manager-override

[RamyHakam]

This pull request introduces a major new feature: Tenant-Aware Cache Isolation for the Symfony Multi-Tenancy Bundle, along with expanded documentation and improvements to customization guidance. The cache isolation feature prevents cross-tenant data leakage by transparently prefixing cache keys with the active tenant's identifier. Documentation now covers this feature, its configuration, usage, best practices, and integration with tenant lifecycle events. Additionally, the customization docs are updated to clarify service override approaches and provide more idiomatic Symfony examples.

New Feature: Tenant-Aware Cache Isolation

• Added full documentation for cache isolation in docs-site/docs/cache/cache-isolation.md, including quick start, architecture details, usage examples, testing, known limitations, and best practices.
• Updated the bundle overview and getting started guides to highlight cache isolation, its benefits, and how to enable it. [1] [2] [3] [4]
• Expanded the events documentation to note that TenantContext tracks the current tenant and enables cache isolation when active.
• Added new sidebar entries and workflow jobs for cache isolation documentation.

Customization & Service Override Improvements

• Revised customization documentation to clarify two approaches for overriding core services: the recommended #[AsAlias] attribute and config-based override, with detailed examples and updated method signatures for interfaces. [1] [2] [3] [4] [5]
• Improved summary and best practices for customizing tenant configuration and management.
• Minor formatting and language improvements for clarity and consistency.

Composer & Dependency Updates

• Added psr/cache and symfony/cache-contracts as required dependencies in composer.json to support cache isolation feature.