Fatal error in CommentEntityTranslation @MigrationSource when source site does not have comment module installed

Problem/Motivation

This is a problem similar to that in #2859315: SQL error from profile_fields when migrating d6 (or d7) to d8 without Profile module. It was introduced in #2981000: Migrate Drupal 7 comment entity translations data to Drupal 8.

Steps to reproduce

Drupal 7 site without comment module.

Drupal 8|9 site with comment module and content_translation module.

Attempting to load the list of migrations results in the following fatal error:

Drupal\Core\Database\DatabaseExceptionWrapper: SQLSTATE[42S02]: Base table or view not found: 1146 Table 'drupal.comment' doesn't exist: SELECT COUNT(*) AS "expression" FROM (SELECT 1 AS "expression" FROM {entity_translation} "et" INNER JOIN {comment} "c" ON c.cid = et.entity_id INNER JOIN {node} "n" ON n.nid = c.nid WHERE ("et"."entity_type" = :db_condition_placeholder_0) AND ("et"."source"<> :db_condition_placeholder_1)) "subquery"; Array ( [:db_condition_placeholder_0] => comment [:db_condition_placeholder_1] => ) in Drupal\migrate\Plugin\migrate\source\SqlBase->doCount() (line 389 of core/modules/migrate/src/Plugin/migrate/source/SqlBase.php).
Drupal\Core\Database\Statement->execute(Array, Array) (Line: 740)
Drupal\Core\Database\Connection->query('SELECT COUNT(*) AS "expression"
FROM
(SELECT 1 AS "expression"
FROM
{entity_translation} "et"
INNER JOIN {comment} "c" ON c.cid = et.entity_id
INNER JOIN {node} "n" ON n.nid = c.nid
WHERE ("et"."entity_type" = :db_condition_placeholder_0) AND ("et"."source"&lt;&gt; :db_condition_placeholder_1)) "subquery"', Array, Array) (Line: 91)
Drupal\Core\Database\Driver\mysql\Connection->query('SELECT COUNT(*) AS "expression"
FROM
(SELECT 1 AS "expression"
FROM
{entity_translation} "et"
INNER JOIN {comment} "c" ON c.cid = et.entity_id
INNER JOIN {node} "n" ON n.nid = c.nid
WHERE ("et"."entity_type" = :db_condition_placeholder_0) AND ("et"."source"&lt;&gt; :db_condition_placeholder_1)) "subquery"', Array, Array) (Line: 510)
Drupal\Core\Database\Query\Select->execute() (Line: 389)

Proposed resolution

Add CommentEntityTranslation::checkRequirements() similar to #2859315: SQL error from profile_fields when migrating d6 (or d7) to d8 without Profile module.

Remaining tasks

None.

User interface changes

None.

API changes

None.

Data model changes

None.

Release notes snippet

None.