Debug-log every API request and response

Add debugFetch wrapper in log.js that logs method, URL, and body on
request, and status code on response. Replace all fetch() calls
across balances, transactions, tokens, background RPC proxy, and
settings validation with debugFetch.

src/popup/views/settings.js

@@ -1,7 +1,7 @@
 const { $, showView, showFlash } = require("./helpers");
 const { state, saveState } = require("../../shared/state");
 const { ETHEREUM_MAINNET_CHAIN_ID } = require("../../shared/constants");
-const { log } = require("../../shared/log");
+const { log, debugFetch } = require("../../shared/log");
 
 const runtime =
     typeof browser !== "undefined" ? browser.runtime : chrome.runtime;
@@ -56,7 +56,7 @@ function init(ctx) {
         }
         showFlash("Testing endpoint...");
         try {
-            const resp = await fetch(url, {
+            const resp = await debugFetch(url, {
                 method: "POST",
                 headers: { "Content-Type": "application/json" },
                 body: JSON.stringify({
@@ -98,7 +98,7 @@ function init(ctx) {
         }
         showFlash("Testing endpoint...");
         try {
-            const resp = await fetch(url + "/stats");
+            const resp = await debugFetch(url + "/stats");
             if (!resp.ok) {
                 showFlash("Endpoint returned HTTP " + resp.status + ".");
                 return;