feat: use go1.16 and resources embedding (#235)

* feat: use go1.16 embedding for resources

We want to embed everything that can be easily embedded. We should, at a
minimum, replace the downloading of resources and bindata.

Ref: https://github.com/ooni/probe/issues/1367.

* fix: get rid of bindata and use go embed instead

* fix: start unbreaking some automatic tests

* fix: fetch resources as part of the mobile build

* fix: convert more stuff to go1.16

I still expect many breakages, but we'll fix them.

* fix: make the windows CI green

* fix: get resources before running QA

* fix: go1.16 uses modules by default

* hopefully fix all other outstanding issues

* fix(QA/telegram.py): add another DC IP address

* Apply suggestions from code review

internal/engine/geolocate/mmdblookup_test.go

@@ -1,12 +1,9 @@
 package geolocate
 
 import (
-	"context"
-	"net/http"
 	"testing"
 
-	"github.com/apex/log"
-	"github.com/ooni/probe-cli/v3/internal/engine/resources"
+	"github.com/ooni/probe-cli/v3/internal/engine/resourcesmanager"
 )
 
 const (
@@ -16,13 +13,8 @@ const (
 )
 
 func maybeFetchResources(t *testing.T) {
-	c := &resources.Client{
-		HTTPClient: http.DefaultClient,
-		Logger:     log.Log,
-		UserAgent:  "ooniprobe-engine/0.1.0",
-		WorkDir:    "../testdata/",
-	}
-	if err := c.Ensure(context.Background()); err != nil {
+	c := &resourcesmanager.CopyWorker{DestDir: "../testdata/"}
+	if err := c.Ensure(); err != nil {
 		t.Fatal(err)
 	}
 }