feat(admin-email): improve management of contact info in emails #3070

[Sidsector9]

Closes #3070

Description

This PR adds a feature to add admin email address and offline mailing address in a common place. This makes it easier to export Give Settings from one URL and import it to a different URL without the need to manually change the admin email address, site URL, site name and the offline mailing address. More details can be found in the video below.

The following email tags are added in this feature:

1. {admin_email}
2. {offline_mailing_address}
3. {site_url}

How Has This Been Tested?

By sending and previewing emails.

Video:

https://www.useloom.com/share/d9756dd20a874037bd9a15c8fa17c78c

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows has proper inline documentation.

[ravinderk]

@Sidsector9 use sprintf to format code

[ravinderk]

@Sidsector9 I think we can use give_email_offline_mailing_address fn here instead of repeating data

[ravinderk]

@Sidsector9 check review

[ravinderk]

@Sidsector9 do we need sprintf here?

[kevinwhoffman]

@slewisma I wanted to give you a heads up that the three new email tags are coming in Give 2.2.0 based on your request:

{admin_email}
{offline_mailing_address}
{site_url}

You'll define the value of these fields in settings and the email tags will be used to pre-populate the templates. If you need to customize a specific form's email notification, you can of course remove the tag and enter your own content into the form's email content.

[Sidsector9]

Call Summary

Participants: @DevinWalker @ravinderk and @Sidsector9
Topic: Changes to be made in the current PR
Result:

• Rename from Contact to 'Contact Information'
• Move tab from 'general' to 'emails'
• Remove the custom admin email radios
• Description for {admin_email} - By default, the {admin_email} tag will use your WordPress admin email. If you would like to customize this address you can do so in the field above.
• Use placeholder for the admin email
• tags in description should be in code tags
• Description for {offline_mailing_address} - Set the mailing address to where you would like your donors to send their offline donations. This will customize the {offline_mailing_address} email tag for the Offline Donations payment gateway.
• Double check if register_give_tags adds tags in the list