Dev- Calculation Module

[NirajChaudhary143]

All Submissions:

• Have you followed the Everest Forms Contributing guideline?
• Does your code follow the WordPress' coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Priviously, no complex calculation like if, else, sqrt, floor, etc. This PR add complex calculation.

How to test the changes in this Pull Request:

1. Create new form and Drag Calculation field ( number and single item )
2. Enable calculation and insert formula.
3. Save form and precview and perform calculation.
4. verify calculated value is corect or not

Note: Calculation supported field : Number, Single Item for caculation result.
'text', 'select', 'radio', 'checkbox', 'number', 'name', 'first-name', 'lsat-name', 'email', 'url', 'payment-checkbox', 'payment-multiple', 'payment-single', 'payment-total'

Logical Operator support : '&&', '||', '/', '==', '>', '>=', '-', '%', '*', '!=', '+', '<', '<=', '!', '-1'

Dependency PR:
PR

Types of changes:

• Bug fix (non-breaking change which fixes an issue)
• Enhancement (modification of the currently available functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you successfully ran tests with your changes locally?
• Have you updated the documentation accordingly?

Changelog entry

Dev- Calculation Module