package:sanitize_html - Added containsDisallowedContent Function for Detecting Prohibited HTML in User-Defined Validation Scenarios

[jawad111]

Motivation:
In scenarios where users only want to detect malicious or disallowed HTML content without sanitizing it, a validation mechanism becomes crucial. This feature allows applications to abort processes or take corrective actions when encountering unsafe HTML, ensuring robustness and security.

Use Cases:

1. Prevent Malicious Submissions:
   Detect malicious content in user-generated inputs, such as comment fields or form submissions, and reject the input early without modifying the HTML.

2. Abort Application Flow:
   Halt the execution of specific workflows (e.g., data processing or rendering) if unsafe HTML is detected, ensuring that the application does not proceed with invalid data.

3. Custom Security Workflows:
   Integrate with security pipelines to log, monitor, or analyze the occurrence of unsafe HTML without sanitizing or altering the input.

4. Audit User Content:
   Validate HTML against custom policies for compliance audits without altering the original content, useful for applications dealing with regulatory constraints or collaborative platforms.

Summary of Changes:

• Introduced containsDisallowedContent, a validation function to detect prohibited HTML tags, attributes, or links.
• Allows developers to define custom rules for id, class, and attribute handling.
• Empowers applications to proactively handle invalid content without performing sanitization.

This feature extends the library's utility by providing a lightweight, focused mechanism for HTML validation.