MAE-475: Display instalment summary amount and prorated number

[erawat]

Overview

This PR adds the schedule summary amount to the instalments table.

This PR also improves the code and templates by:

• Using CiviCRM tax term for displaying tax text instead of hard code in to the template.
• Separating JavaScript, stylesheet from the template including existing payment toggle.
• Adding additional tests as well as add Instalment page test.
• Refactor the class name, so it has a meaningful name.

Before

Subtotal, tax amount, total amount and prorated unit (if fixed membership type is selected) were not shown on the table.

After

Subtotal, tax amount, total amount and prorated unit (if fixed membership type is selected) are displayed on the table.

Example of what the summary amount look like on different membership types.

Prorated by months

Prorated by days

Rolling membership