Adding TokenListController to fetch the token list from token services API

[NiranjanaBinoy]

The purpose of the controller is to poll the new token detection API tokens/:chainId at regular intervals to get the list of tokens dynamically instead of getting it from @metamask/contract-metadata. The controller also calls on the /sync/:chainId API which initiates sync on the token list in the background and tokens/:chainId?address=<tokenAddress> which returns the metadata of the token whose address is provided.

This controller will be used by detect-token.js(DetectTokensController) from metamask-extension repo and AssetsDetectionController.ts from metamask/controllers repo. AssetsDetectionController.ts is updated as a part of this PR to use the TokeListcontroller as a source of the token list instead of @metamask/contract-metadata.

[mobularay]

@NiranjanaBinoy do you still need more input / feedback from Mobile? Thank you!

[Cal-L]

Left some comments. Great work! 👍

[adonesky1]

Should there be a method present on the controller to update the chainId on the this.networkController.on(NETWORK_EVENTS.NETWORK_DID_CHANGE event?

[brad-decker]

@adonesky1 I thiknk that is setup differently in controllers repo: see these lines

https://github.com/MetaMask/controllers/pull/478/files#diff-c2ec75b01a3b2e2e1284df7c48ad4c80a26ea7f1455167cc8390d91ca865b854R121-R123

EDIT:

onNetworkStateChange: (callback) => { 
  this.networkController.on(NETWORK_EVENTS.NETWORK_DID_CHANGE, () => { 
   const chainId = this.networkController.getCurrentChainId();
   callback({ chainId });
  });
},

Alternatively we might want to think about emitting a CHAIN_CHANGED event somewhere too that gets the new chainId emitted. NETWORK_DID_CHANGE in extension only emits the network type (mainnet/rinkeby/rpc)

[adonesky1]

@adonesky1 I thiknk that is setup differently in controllers repo: see these lines

Oh weird I had pulled down and was looking at an older version of this PR that didn't contain those lines... LGTM

[brad-decker]

One NIT that may be easily dismissed, curious about the follow up question though! Leaving this as 'request changes' but should be easy to convert me to a ✅

[brad-decker]

LGTM