Selectable serifed variants of digits

[jmcwilliams403]

• [x] The requested variant shape does not go too far away from Iosevka's design.
• [x] The requested variant does not conflict with any characters in Unicode that Iosevka currently supports.
• [x] At least two monospace/programming fonts, created by different designers, supported the requested variant. Provide images below.

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One of the fonts below is supported by a stylistic set (ss02).

0123456789

Anonymous Pro: Courier New: FreeMono:

[Logo121]

cf. #2085 For some more serifed digit variants