[SR-14908] Implement `func copy()` in subclasses of `Formatter`.

[YOCKOW]

Previous ID	SR-14908
Radar	None
Original Reporter	@YOCKOW
Type	Task

Additional Detail from JIRA

Votes	0
Component/s	Foundation
Labels	Task
Assignee	None
Priority	Medium

md5: a1dfdbee70cd126cf2be0502d2c0828f

Sub-Tasks:

• SR-14108 DateFormatter is not copied by copy() with SwiftFoundation.
• SR-14909 Implement ByteCountFormatter.copy()
• SR-14910 Implement DateComponentsFormatter.copy
• SR-14911 Implement DateIntervalFormatter.copy
• SR-14912 Implement MeasurementFormatter.copy
• SR-14913 Implement NumberFormatter.copy
• SR-14914 Implement PersonNameComponentsFormatter.copy
• SR-14933 Implement ISO8601DateFormatter.copy

Issue Description:

As @spevans commented on SR-14108, each subclass of Formatter needs to implement its own override of copy().
This task tracks them.