hrreport: Display options should match group options

When creating a new report based on the CiviHR Summary template, there are a number of checkboxes under the headings of "Display Columns" and "Group by Columns". There are some discrepancies in what checkboxes are available in the two. Ideally, we should add complete support for any of these items – if that's challenging, then we could instead remove support for incomplete items.

These items are in "Display" but not in "Group by":

-Contract Type
-Employee Contribution (%)
-Employer Contribution (%)
-Healthcare Provider
-Hours Type
-Hours Unit
-Leave Type
-Pay Unit
-Period Type
-Plan Type
-Type

These items have different names:

-Pay Grade
+Job Pay Grade
-Title
+Job Title