Revert "Add new optional beta email parser thats based on ImapEngine instead of Webklex"

This reverts commit 9cb1ff7330.

plugins/vendor/doctrine/lexer/UPGRADE.md

@@ -1,22 +0,0 @@
-Note about upgrading: Doctrine uses static and runtime mechanisms to raise
-awareness about deprecated code.
-
-- Use of `@deprecated` docblock that is detected by IDEs (like PHPStorm) or
-  Static Analysis tools (like Psalm, phpstan)
-- Use of our low-overhead runtime deprecation API, details:
-  https://github.com/doctrine/deprecations/
-
-# Upgrade to 3.0.0
-
-`Doctrine\Common\Lexer\Token` no longer implements `ArrayAccess`.
-Parameter type declarations have been added to
-`Doctrine\Common\Lexer\AbstractLexer` and `Doctrine\Common\Lexer\Token`.
-You should add both parameter type declarations and return type declarations to
-your lexers, based on the `@return` phpdoc.
-
-# Upgrade to 2.0.0
-
-`AbstractLexer::glimpse()` and `AbstractLexer::peek()` now return
-instances of `Doctrine\Common\Lexer\Token`, which is an array-like class
-Using it as an array is deprecated in favor of using properties of that class.
-Using `count()` on it is deprecated with no replacement.