use token custom icons where possible

[adonesky1]

Fixes: #8252

Explanation: Adds custom icon for a token to the send token flow in the asset-dropdown

Manual testing steps:

• Add a custom token via the methods outlined in EIP-747
• Attempt to send some of this token
• Confirm that the custom icon that was supplied when first importing the token is visible beside token name(rather than generic identicon).

Here is a method that can be called in the browser console to initialize the addition of a token with a custom icon into MetaMask:

ethereum.request({ method: 'wallet_watchAsset', params: { type: 'ERC20', options: { address: '0xb60e8dd61c5d32be8058bb8eb970870f07233155', symbol: 'FOO', decimals: 18, image: 'https://w7.pngwing.com/pngs/1018/815/png-transparent-luminiferous-aether-symbol-diethyl-ether-symbol-miscellaneous-purple-chemical-element.png', }, }, }) .then((success) => { if (success) { console.log('FOO successfully added to wallet!') } else { throw new Error('Something went wrong.') } }) .catch(console.error)

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[brad-decker]

LGTM