Script Loader: Add an API for filtering inline style attributes

[Sukhendu2002]

What this PR does

Adds a structured API for generating and filtering inline <style> tags:

• Adds wp_get_inline_style_tag().
• Adds wp_print_inline_style_tag().
• Adds the wp_inline_style_attributes filter.
• Routes WP_Styles output through the new API.
• Covers normal, direct, no-source, and concatenated style output.
• Uses WP_HTML_Tag_Processor for safe attribute and CSS handling.

This allows plugins to add attributes such as CSP nonces without modifying complete HTML strings.

The script portion of the original ticket is already covered by wp_inline_script_attributes, so this PR focuses on the remaining inline-style functionality.

Trac ticket: https://core.trac.wordpress.org/ticket/51325

Use of AI Tools

AI assistance: Yes
Tool(s): OpenAI Codex
Model(s): GPT-5.6
Used for: Initial code skeleton, test suggestions and code review; final implementation and tests were reviewed and edited by me.

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This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

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