R1:d42b3eb0b17a

Fix "Map omits required key" exception by comparing result order against modern field keys

Summary:
Sorting a Maniphest search query by custom fields throws a "Map returned omits required key" exception.

The `isCustomFieldOrderKey()` check still tested against legacy field key format (for example `[custom:]std:maniphest:deadline.due`) while the code passes modern field key format (for example `custom.deadline.due`).

After fixing this, `PhutilTypeSpec::checkMap()` throws an exception when a non-optional…