Added Conditional Introduction and Biconditional Introduction tests

[charlestian23]

Description

Added conditional introduction and biconditional introduction tests.

Closes #667, #668

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Enhancement (improvement to an already existing feature)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

How Has This Been Tested?

Checklist:

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (if applicable)
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[Corppet]

Looks good. Appreciate the spacing to help make the code more readable. Comments are also informative and to the point.