Provide a means to identify comparisons and assignments between Datetime and Date type values

[Phil W]

The implicit conversion of a Date to a Datetime, in assignments and in comparisons, is fundamentally bad because the Datetime result of the conversion is midnight in UTC, rather than midnight in the contextual user’s time zone (which is how Datetime values normally operate). This leads to bugs.

Finding where this is done in code is currently not possible using IC’s apex editor, inspections or searches.

[Scott Wells]

Duplicate of #1009.