Add the process map legend: Pending / Not Executed

Issue & Reproduction Steps

The legend only displays information for Task with completed or in progress status. However, when a user had not participated in a Task (gray color), that information is not displayed in the legend.

Related Tickets & Packages

• https://processmaker.atlassian.net/browse/FOUR-9310

Code Review Checklist

• I have pulled this code locally and tested it on my instance, along with any associated packages.
• This code adheres to ProcessMaker Coding Guidelines.
• This code includes a unit test or an E2E test that tests its functionality, or is covered by an existing test.
• This solution fixes the bug reported in the original ticket.
• This solution does not alter the expected output of a component in a way that would break existing Processes.
• This solution does not implement any breaking changes that would invalidate documentation or cause existing Processes to fail.
• This solution has been tested with enterprise packages that rely on its functionality and does not introduce bugs in those packages.
• This code does not duplicate functionality that already exists in the framework or in ProcessMaker.
• This ticket conforms to the PRD associated with this part of ProcessMaker.