fix nft token instance images

[ayrat555]

Changelog

• allow images from ['properties']['image']['description'] in nft token
• allow images from all sources

[coveralls]

Pull Request Test Coverage Report for Build 38be72c2-f4e1-4432-aff9-56c2bafb7a94

• 7 of 10 (70.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.03%) to 77.812%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
apps/block_scout_web/lib/block_scout_web/views/tokens/instance/overview_view.ex	7	10	70.0%

Totals
Change from base Build 68148591-b09c-4e1a-bd49-1797782f2f4e:	0.03%
Covered Lines:	5320
Relevant Lines:	6837

---

💛 - Coveralls

[vbaranov]

.

[pasqu4le]

Just one suggestion

[pasqu4le]

Just my opinion, but this function definition seems unnecessarily repetitive.
It could be changed into:

  def image_src(instance) do
    [ 
      instance.metadata["image_url"],
      instance.metadata["image"],
      instance.metadata["properties"]["image"]["description"],
      image_src(nil)
    ]
    |> Enum.find(& not is_nil(&1) and String.trim(&1) != "")
  end