Additional fixes to workflow templates

[seamuslee001]

This is a reviewers cut of #15742

Overview

This PR contains some minor additions / missing improvements to the other pr's on the workflow messages upgrade in 5.20

Before

some minor improvements missing from the other PR's

After

some minor improvements included in 5.20

Technical Details

For responsive tables that look well on desktop as well as mobile view this is used in the container table:

width:100%; max-width:700px;

Comments

1. missing greeting in event_offline template
2. changes to payment/refund template to better reflect amount paid & totals
3. changes to have the html tables have the same looks when viewed on a mobile

OLD TEMPLATE Payment receipt

NEW TEMPLATE Payment receipt [completed]

NEW TEMPLATE Refund notification

[civibot]

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[magnolia61]

Added #15751 to this collection :-)