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/background/index.js

@@ -8,6 +8,7 @@ const {
 } = require("../shared/constants");
 const { state, loadState, saveState } = require("../shared/state");
 const { refreshBalances } = require("../shared/balances");
+const { debugFetch } = require("../shared/log");
 
 const storageApi =
     typeof browser !== "undefined"
@@ -67,7 +68,7 @@ function extractHostname(origin) {
 // Proxy an RPC call to the Ethereum node
 async function proxyRpc(method, params) {
     const rpcUrl = await getRpcUrl();
-    const resp = await fetch(rpcUrl, {
+    const resp = await debugFetch(rpcUrl, {
         method: "POST",
         headers: { "Content-Type": "application/json" },
         body: JSON.stringify({