Added logic to use an internal SpamToken image to TokenImageFetcherImpl instead of fetching it over the network

[eviltofu]

Closes #6446

[hboon]

@eviltofu I just realized that we can't remove the spam token icon files from the iconassets repo rightaway since we need to give it some time after both the Android and iOS app has been live. Can you help create/move an issue into the iconassets repo to remove those files and assign to yourself, referring back to this comment so we remember to finish it up?

[eviltofu]

@hboon

So I schedule a task to remove the spam token icons files 1 month later?

Also, this process of adding to the adjustments.js file after checking iconassets needs to be streamlined. Maybe we can just have a spam.json file and then from that generate the adjustments.js file and remove the spam logo from iconassets? Generate a script file from spam.json that checks the iconassets repo. Also instead of removing the logo.png file, maybe just rename it to spam.png to hide it from the app? Otherwise if we make a mistake in classifying a token as spam and later discovering it was an error, we would need to go find and download the token logo icon again.

[hboon]

So I schedule a task to remove the spam token icons files 1 month later?

Yes, but can you do it this way: Set up a new test class that does this:

class Foo_Some_Name_Reminders: XCTestCase {
    func testRemoveSpamTokenIconFiles() {
        //Fails with a TODO to create an issue with "some title" on and after 20230601
    }
}

Thought I wrote about this approach in the Android repo for some other issue, but I forgot where

[hboon]

Also, this process of adding to the adjustments.js file after checking iconassets needs to be streamlined. Maybe we can just have a spam.json file and then from that generate the adjustments.js file and remove the spam logo from iconassets? Generate a script file from spam.json that checks the iconassets repo.

Improving the process is good. adjustments.json currently only holds contracts for the Spam group though. Maybe wait a bit to see what we do with the file before we modify the code/process? Seems unnecessary now.

Also instead of removing the logo.png file, maybe just rename it to spam.png to hide it from the app? Otherwise if we make a mistake in classifying a token as spam and later discovering it was an error, we would need to go find and download the token logo icon again.

It wouldn't be because it's the same icon file contents (and it's still in git any way)

[eviltofu]

@oa-s still reviewing?

[hboon]

Didn't test. But I think overlayServerIcon: still has to be either nil or not-nil using the switch-case a few lines later. That's how the current hardcoded spam (or any token image) loaded from the iconassets repo are displayed, right?

[eviltofu]

Updated. Please check @hboon

[hboon]

Seems like this will never be true because it was checked in the switch within the iconIamgeForContractAndhainID(image:address:chain:) call, so the if-block can be removed.

[eviltofu]

Removed.