Add operand types to DisallowedLooseComparisonRule error message

[mpesari]

This makes it possible to ignore disallowedLooseComparison issues for certain builtin PHP classes with overloaded comparison operators:

• BcMath\Number
• DateTime (Resolves disallowedLooseComparison - allow only DateTime/DateTimeImmutable #232)

Currently the error message doesn't include types:

Loose comparison via "==" is not allowed.

This adds operands types to make the errors ignorable:

Loose comparison via "==" between DateTime and DateTime is not allowed.