WL-97 Bulk Registration Email Confirmation

WL-97 Bulk Registration Email Confirmation
Below is the commit summary.
- Make email text bold as per requirement.
- Improve email template quality and reorder points.
- Add text in billing details page : "if no additional billing details are populated the payment confirmation will be sent to the user making the purchase"
- Update text on receipt page "You have successfully purchase 3 course registration codes"