Email Editor: Integrate the convert class from the HTML to Text library (woocommerce#59859)

* # This is a combination of 5 commits.
# This is the 1st commit message:

Email Editor: Integrate the convert class from the HTML to Text library and remove the dependency.

# This is the commit message #2:

Fix linting errors.

# This is the commit message #3:

Fix more linting errors.

# This is the commit message #4:

Fix package linting errors.

# This is the commit message woocommerce#5:

Fix additional package linting errors.

* Email Editor: Integrate HTML to Text library and remove external dependency

- Internalized soundasleep/html2text functionality
- Added Html2Text and Html2Text_Exception classes
- Updated composer.json to remove dependency
- Fixed all PHPStan and WordPress coding standards violations
- Ensured PHP 7.4+ compatibility and standalone package support

* Fix potential security issues with exceptions.

* Ignore error_logs since they're for security purposes.

* Remove unused .

* Email editor: Add unit and integration tests for html2text, and remove unnecessary import.

* Fix PHP and linter issues.

* Attempt to keep the tests happy while fixing the PHPStan error.

* Change from double quotes to single quotes.

* Add changefile(s) from automation for the following project(s): packages/php/email-editor

* Add security information to package

* Add copyright and license headers to new files

* Add package license

- GPLv2 or later
- Also incorporates work with different copyright and license.

Internal reference:
p2y3YZ-9Ry-p2#comment-22676

* Add new licensing / security reporting policy

* Add 2 new files to mirror repo as well

---------

Co-authored-by: github-actions <github-actions@github.com>
Co-authored-by: Jeremy Herve <jeremy@jeremy.hu>

Author: 3 people

packages/php/email-editor/SECURITY.md

@@ -0,0 +1,21 @@
+# Security Policy
+
+Full details of the Automattic Security Policy can be found on [automattic.com/security](https://automattic.com/security/).
+
+## Reporting a Vulnerability
+
+**For responsible disclosure of security issues and to be eligible for our bug bounty program, please submit your report based on instructions found on [automattic.com/security](https://automattic.com/security).**
+
+## Guidelines
+
+We're committed to working with security researchers to resolve the vulnerabilities they discover. You can help us by following these guidelines:
+
+*   Follow [HackerOne's disclosure guidelines](https://www.hackerone.com/disclosure-guidelines).
+*   Pen-testing Production:
+    *   Please **setup a local environment** instead whenever possible. Most of our code is open source (see above).
+    *   If that's not possible, **limit any data access/modification** to the bare minimum necessary to reproduce a PoC.
+    *   **Don't automate form submissions!** That's very annoying for us, because it adds extra work for the volunteers who manage those systems, and reduces the signal/noise ratio in our communication channels.
+    *   To be eligible for a bounty, please follow all of these guidelines.
+*   Be Patient - Give us a reasonable time to correct the issue before you disclose the vulnerability.
+
+We also expect you to comply with all applicable laws. You're responsible to pay any taxes associated with your bounties.

packages/php/email-editor/changelog/59859-wooplug-4979-integrate-the-html-to-text-library-into-the-email-editor

@@ -0,0 +1,4 @@
+Significance: patch
+Type: dev
+Comment: Integrated the convert class from the external HTML to Text library and removed the dependency from the Email Editor package.
+

packages/php/email-editor/changelog/59859-wooplug-4979-integrate-the-html-to-text-library-into-the-email-editor-2

@@ -0,0 +1,4 @@
+Significance: minor
+Type: add
+
+Add licensing and security policy.

packages/php/email-editor/composer.json

@@ -18,8 +18,7 @@
 	},
 	"require": {
 		"php": ">=7.4",
-		"pelago/emogrifier": "^7.3",
-		"soundasleep/html2text": "^2.1"
+		"pelago/emogrifier": "^7.3"
 	},
 	"require-dev": {
 		"automattic/jetpack-changelogger": "3.3.0",