Update emogrifier

[mikeyarce]

Fixes #2755

Changes Proposed in this Pull Request

• Update to use new version of Emogrifier
• Load Emogrifier through a composer dependency
• New plugin build so that we can include the composer dependency

Testing Instructions

• Check out PR
• Run npm run build
• Make sure that the new plugin build matches the old plugin build. You can run npm run build:assets && npm run archive which is the previous build and check folders to make sure it's what we expect. It should be identical except for the tests are gone from the usage-tracking folder, and now we do include the vendor folder for emogrifier.
  Here is my folder comparison including hidden files:
• Now use this plugin on a site that can send emails
• Add a few alerts
• Send the alerts to a gmail account and make sure the top and bottom margin is there!

Example of margin:

Release Notes

• Fix: Email notifications - top and bottom margin not displaying properly for some email clients.

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Plugin build for 9215cf69c667681fe97648d9e1448b07f6791b1e
📦 Download plugin zip
▶️ Open in playground

[mikeyarce]

Thanks @gikaragia - made the changes 😄