refs https://github.com/TryGhost/Ghost/issues/11971
- Added statusCode from bulk email provider to API response
- Updated error messages for different bulk email(mailgun) failure states
- Added `context` to preview mail API error message with mail provider's error message
* refactored `core/frontend/apps` to destructure common imports
* refactored `core/frontend/services/{apps, redirects, routing}` to destructure common imports
* refactored `core/frontend/services/settings` to destructure common imports
* refactored remaining `core/frontend/services` to destructure common imports
* refactored `core/server/adapters` to destructure common imports
* refactored `core/server/data/{db, exporter, schema, validation}` to destructure common imports
* refactored `core/server/data/importer` to destructure common imports
* refactored `core/server/models/{base, plugins, relations}` to destructure common imports
* refactored remaining `core/server/models` to destructure common imports
* refactored `core/server/api/canary/utils/serializers/output` to destructure common imports
* refactored remaining `core/server/api/canary/utils` to destructure common imports
* refactored remaining `core/server/api/canary` to destructure common imports
* refactored `core/server/api/shared` to destructure common imports
* refactored `core/server/api/v2/utils` to destructure common imports
* refactored remaining `core/server/api/v2` to destructure common imports
* refactored `core/frontend/meta` to destructure common imports
* fixed some tests referencing `common.errors` instead of `@tryghost/errors`
- Not all of them need to be updated; only updating the ones that are
causing failures
* fixed errors import being shadowed by local scope
no issue
- fixed plaintext templates being word wrapped and breaking across replacement strings
- updated `postEmailSerializer.serialize` to return the email template plus a replacements array that can be used for creating Mailgun-like recipient variable objects or more straight forward replacement
- updated email-preview API to work with the replacements data to show fallback data when previewing
