[SR-8439] Provide UUID RFC 4122 compliant string

[swift-ci]

Previous ID	SR-8439
Radar	None
Original Reporter	--marc (JIRA User)
Type	New Feature

Additional Detail from JIRA

Votes	0
Component/s	Foundation
Labels	New Feature
Assignee	None
Priority	Medium

md5: 27c88bab4d8dd03210ae237df173c850

relates to:

• SR-9091 UUID does not follow RFC for string representation

Issue Description:

This proposed feature addition is that `UUID` provide some call which returns an RFC 4122 section 3 compliant ⇗ compliant lowercased UUID string.

The hexadecimal values "a" through "f" are output as lower case characters and are case insensitive on input.

This proposed addition is NOT to replace or remove the `uuidString` method which is compliant with Objective-C NSUUID. see SR-865 ⇗

Possible implementation:

1. Add a some `rfc4122String` which has an autocomplete prompt like "Returns a lowercased, RFC 4122 compliant, string created from the UUID, such as 'e621e1f8-c36c-495a-93fc-0c247a3e6e5f'"

2. Update `uuidString` autocomplete prompt to expressly state uppercased. For example, "Returns an UPPERCASED string created from the UUID, such as 'E621E1F8-C36C-495A-93FC-0C247A3E6E5F'" and perhaps also add something like "… consistent with NSUUID."