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/settings/tinyproxy.go

@@ -0,0 +1,60 @@
+package settings
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/qdm12/private-internet-access-docker/internal/models"
+	"github.com/qdm12/private-internet-access-docker/internal/params"
+)
+
+// TinyProxy contains settings to configure TinyProxy
+type TinyProxy struct {
+	Enabled  bool
+	User     string
+	Password string
+	Port     uint16
+	LogLevel models.TinyProxyLogLevel
+}
+
+func (t *TinyProxy) String() string {
+	if !t.Enabled {
+		return "TinyProxy settings: disabled"
+	}
+	auth := "disabled"
+	if t.User != "" {
+		auth = "enabled"
+	}
+	settingsList := []string{
+		"TinyProxy settings:",
+		fmt.Sprintf("Port: %d", t.Port),
+		"Authentication: " + auth,
+		"Log level: " + string(t.LogLevel),
+	}
+	return "TinyProxy settings:\n" + strings.Join(settingsList, "\n |--")
+}
+
+// GetTinyProxySettings obtains TinyProxy settings from environment variables using the params package.
+func GetTinyProxySettings(params params.ParamsReader) (settings TinyProxy, err error) {
+	settings.Enabled, err = params.GetTinyProxy()
+	if err != nil || !settings.Enabled {
+		return settings, err
+	}
+	settings.User, err = params.GetTinyProxyUser()
+	if err != nil {
+		return settings, err
+	}
+	settings.Password, err = params.GetTinyProxyPassword()
+	if err != nil {
+		return settings, err
+	}
+	settings.Port, err = params.GetTinyProxyPort()
+	if err != nil {
+		return settings, err
+	}
+	settings.LogLevel, err = params.GetTinyProxyLog()
+	if err != nil {
+		return settings, err
+	}
+	return settings, nil
+}