Rewrite of the entrypoint in Golang (#71)

- General improvements
    - Parallel download of only needed files at start
    - Prettier console output with all streams merged (openvpn, unbound, shadowsocks etc.)
    - Simplified Docker final image
    - Faster bootup
- DNS over TLS
    - Finer grain blocking at DNS level: malicious, ads and surveillance
    - Choose your DNS over TLS providers
    - Ability to use multiple DNS over TLS providers for DNS split horizon
    - Environment variables for DNS logging
    - DNS block lists needed are downloaded and built automatically at start, in parallel
- PIA
    - A random region is selected if the REGION parameter is left empty (thanks @rorph for your PR)
    - Routing and iptables adjusted so it can work as a Kubernetes pod sidecar (thanks @rorph for your PR)

internal/dns/command_test.go

@@ -0,0 +1,69 @@
+package dns
+
+import (
+	"fmt"
+	"testing"
+
+	commandMocks "github.com/qdm12/golibs/command/mocks"
+	loggingMocks "github.com/qdm12/golibs/logging/mocks"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/qdm12/private-internet-access-docker/internal/constants"
+)
+
+func Test_Start(t *testing.T) {
+	t.Parallel()
+	logger := &loggingMocks.Logger{}
+	logger.On("Info", "%s: starting unbound", logPrefix).Once()
+	commander := &commandMocks.Commander{}
+	commander.On("Start", "unbound", "-d", "-c", string(constants.UnboundConf), "-vv").
+		Return(nil, nil, nil, nil).Once()
+	c := &configurator{commander: commander, logger: logger}
+	stdout, err := c.Start(2)
+	assert.Nil(t, stdout)
+	assert.NoError(t, err)
+	logger.AssertExpectations(t)
+	commander.AssertExpectations(t)
+}
+
+func Test_Version(t *testing.T) {
+	t.Parallel()
+	tests := map[string]struct {
+		runOutput string
+		runErr    error
+		version   string
+		err       error
+	}{
+		"no data": {
+			err: fmt.Errorf(`unbound version was not found in ""`),
+		},
+		"2 lines with version": {
+			runOutput: "Version  \nVersion 1.0-a hello\n",
+			version:   "1.0-a",
+		},
+		"run error": {
+			runErr: fmt.Errorf("error"),
+			err:    fmt.Errorf("unbound version: error"),
+		},
+	}
+	for name, tc := range tests {
+		tc := tc
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+			commander := &commandMocks.Commander{}
+			commander.On("Run", "unbound", "-V").
+				Return(tc.runOutput, tc.runErr).Once()
+			c := &configurator{commander: commander}
+			version, err := c.Version()
+			if tc.err != nil {
+				require.Error(t, err)
+				assert.Equal(t, tc.err.Error(), err.Error())
+			} else {
+				assert.NoError(t, err)
+			}
+			assert.Equal(t, tc.version, version)
+			commander.AssertExpectations(t)
+		})
+	}
+}