Convert the error handler to a class

Followup #2999721: [META] Deprecate the legacy include files

Problem/Motivation

Deprecate legacy errors.inc file functions.

Proposed resolution

Convert all error handler related functions to the methods in the Error class.

Remaining tasks

• Deprecate functions
• Replace usages in the code
• Add legacy tests

User interface changes

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API changes

• new methods in \Drupal\Core\Utility\Error class
• deprecated error handler related functions

Data model changes

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Release notes snippet

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