Issue #2917883 by quietone, TR, Jo Fitzgerald, masipila, phenaproxima: Rename 'migration_templates' directories in core modules to 'migrations'

Issue #2887142 by maxocub, phenaproxima, Jo Fitzgerald, Adita, heddn, andypost: NodeType source plugin should include comment information

Issue #2853872 by heddn, maxocub, masipila, phenaproxima, quietone, andypost, larowlan: Migration for forum and article comments: duplicate comment types and incorrect comment_entity_statistics

Revert "Issue #2560795 by mikeryan, phenaproxima, penyaskito, willwh, benjy: Source plugins have a hidden dependency on migrate_drupal"

This reverts commit 89815ba3.

Issue #2560795 by mikeryan, phenaproxima, penyaskito, willwh, benjy: Source plugins have a hidden dependency on migrate_drupal