AO3-6774 Create invite_increase_notification mailer preview

[amecreate]

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Issue

https://otwarchive.atlassian.net/browse/AO3-6774

Purpose

Add mailer preview for the invite_increase_notification email.

Update the locale keys used in the mail to the current I18n standards.

Monkeypatch after_commit_everywhere to save the locale when deliver_after_commit is called (credit @Bilka2)

Testing Instructions

See Jira.

References

With the updated locale keys, Translation needs to move the keys in Phrase.

Credit

Amy Lee

[redsummernight]

There are some Rubocop warnings on this file. You should fix the Layout/TrailingEmptyLines one.

The Rails/Output I think is actually fine. You can update Rubocop's rules from:

otwarchive/.rubocop.yml

Lines 155 to 158 in 8467810

	Rails/Output:
	Exclude:
	# Allow migrations to print pt-osc comments to console:
	- 'db/migrate/*.rb'

to:

Rails/Output:
  Exclude:
    # Allow patches to print warnings to console:
    - 'config/initializers/monkeypatches/*.rb'
    # Allow migrations to print pt-osc comments to console:
    - 'db/migrate/*.rb'