Add Missing rest_prepare_ Filters to Several REST API Controllers

[vipulpatil]

Issue
Several WordPress REST API controllers lack rest_prepare_ filters, creating inconsistent extensibility across different resource types. The affected controllers do not provide a standard mechanism for developers to modify API responses, limiting the ability to customize or extend REST API outputs.

Proposed Solution
Implement rest_prepare_ filters for the following controllers:

class-wp-rest-block-patterns-controller
class-wp-rest-block-pattern-categories-controller
class-wp-rest-global-styles-controller
class-wp-rest-templates-controller
class-wp-rest-template-revisions-controller
class-wp-rest-template-autosaves-controller
class-wp-rest-search-controller

Add a standard filter implementation in each controller's prepare_item_for_response() method:

## Summary
This PR adds new rest_prepare_ filters to block pattern-related REST API controllers, enhancing the extensibility of WordPress REST API for block patterns and block pattern categories.

### Changes Made

• Added rest_prepare_block_pattern filter to class-wp-rest-block-patterns-controller
• Added rest_prepare_block_pattern_category filter to class-wp-rest-block-patterns-categories-controller

Trac ticket: https://core.trac.wordpress.org/ticket/63056