[tokens.json] Automatically apply the Spam token icon instead of the one from sources like iconassets repo

[hboon]

No description provided.

[eviltofu]

@hboon can you elaborate on this? Currently this is showing when a token is spam.

[hboon]

@eviltofu we currently display the spam icon, as in the screenshot above for tokens we think are spam. We want to continue this effect.

Current implementation:

We don't use the Spam group from tokens.json to detect them. Instead, if we think 0x0b91b07beb67333225a5ba0259d55aee10e3a578 is spam, we'll upload an icon file to the iconassets repo with the word "spam" in it https://github.com/AlphaWallet/iconassets/blob/4d77b8d2160b5009e86cb46e138e13e113e74a0d/0x0b91b07beb67333225a5ba0259d55aee10e3a578/logo.png

So it's a lot more work than necessary and wasteful of bandwidth, storage etc

How the implementation should be:

We should check against the new-ish isSpam(address:chainId:) (I think that's what it's called) when fetching a token image and use a single copy of the icon file we will ship with the app and not involve the network at all. This might be a good place to start at and work upstream:

alpha-wallet-ios/modules/AlphaWalletFoundation/AlphaWalletFoundation/Tokens/TokenImageFetcher.swift

Line 260 in 31fe94d

case alphaWallet = "https://raw.githubusercontent.com/AlphaWallet/iconassets/master/"

[eviltofu]

Needs #6645 to be merged.