Fixes for update transient and cron jobs.

Changes include:

• NEW: make license valid method after renewal.
• ADDED: active count param to update times activated after expiry.
• ADDED: product slug check before sending request.
• FIXED: response product meta check on update transient.
• REVIEW: refactor codes, comments.

License Manager Server must also be updated on the server.

Support for latest License Manager Server Update

Server Manager Updates:

OOP approach for managing license, security enhancement, update meta key generation (commit b07dd51).

• SECURITY ENHANCEMENT: Forbid direct REST API access. Applied filter hook to disable it, if not needed.
• ADDED: Strict check for product slug on the request parameter. Without it, the request fails.
• ADDED: Typehints.
• UPDATED: Meta key is now generated using product slug and client URL. This allows for multiple client managers on the same site. Old metadata is upgraded automatically.
• UPDATED: Error in REST API response data.
• UPDATED: Request error for activating or deactivating route.
• UPDATED: Changed action hook to filter hook for validating the request.
• REMOVED: Transient usage.
• REMOVED: Unnecessary error message with data when validate license happening.
• FIXED: Default option value if an empty string was saved.
• REVIEW: Refactor codes and comments.

Fixed logical errors on field validation.

FIXED: Validation checks logic errors.

• check if license form fields are even present.
• check and sanitize posted data using the new "clean" method.

ENHANCEMENTS:

• refactor "generate_form" method.
• type hints.
• Script: IIFE and other refactorings.
• Style: only enqueue on the license page.

BREAKING CHANGE:

• filter tag is now prefixed by directory name.

Added validation method and other code reviews.

Changelog:
ADDED: debug check for prepare_request method & before saving the response.
REVIEW: validation with slug instead of name.
REVIEW: response notice message.
REVIEW: authorization header type
REVIEW: other codes and comments.

Version 1.0

Basic license manager client which talks to License Manager for WooCommerce plugin on a server WordPress installation.