[SR-14911] Implement DateIntervalFormatter.copy

[YOCKOW]

Previous ID	SR-14911
Radar	None
Original Reporter	@YOCKOW
Type	Sub-task

Additional Detail from JIRA

Votes	0
Component/s	Foundation
Labels	Sub-task
Assignee	None
Priority	Medium

md5: 8f970988a1ed5cca0e812d047b1095f2

Parent-Task:

• SR-14908 Implement func copy() in subclasses of Formatter.

Issue Description: