Faroese available twice in language selection

[HamsterDeveloper]

When choosing the language of an edition, Faroese apppears twice.

Evidence / Screenshot (if possible)

[cdrini]

Faroese appears twice here: https://openlibrary.org/languages , under https://openlibrary.org/languages/far and https://openlibrary.org/languages/fao . We likely want to merge these two, and then update all records? This isn't something we've hit with languages before.

[lephemere]

far language code for Faroese was deprecated in MARC 21 (https://www.loc.gov/marc/languages/language_code.html). far is however a valid ISO 639-3 language code for the Fataleka language (Spoken in the Solomon Islands).

[lephemere]

There are actually more duplicate language names with different MARC codes:

Language Name	MARC Code	Discontinued MARC Code
Croatian	hrv	scr
Esperanto	epo	esp
Ethiopic	gez	eth
Faroese	fao	far
Frisian	fry	fri
Galician	glg	gag
Guarani	grn	gua
Interlingua (International Auxiliary Language Association)	ina	int
Irish	gle	iri
Khmer	khm	cam
Malagasy	mlg	mla
Oromo	orm	gal
Sami	smi	lap
Samoan	smo	sao
Serbian	srp	scc
Shona	sna	sho
Sinhalese	sin	snh
Sotho	sot	sso
Swazi	ssw	swz
Tagalog	tgl	tag
Tajik	tgk	taj
Tatar	tat	tar
Tswana	tsn	tsw

[tfmorris]

This isn't something we've hit with languages before.

863 contains my original 2018 report of this problem along with a recommended course of action.