feat(server): role based authentication system (#2434)

- Parse toml configuration file, see https://github.com/qdm12/gluetun-wiki/blob/main/setup/advanced/control-server.md#authentication
- Retro-compatible with existing AND documented routes, until after v3.41 release
- Log a warning if an unprotected-by-default route is accessed unprotected
- Authentication methods: none, apikey, basic
- `genkey` command to generate API keys

Co-authored-by: Joe Jose <45399349+joejose97@users.noreply.github.com>

internal/cli/genkey.go

@@ -0,0 +1,66 @@
+package cli
+
+import (
+	"crypto/rand"
+	"flag"
+	"fmt"
+)
+
+func (c *CLI) GenKey(args []string) (err error) {
+	flagSet := flag.NewFlagSet("genkey", flag.ExitOnError)
+	err = flagSet.Parse(args)
+	if err != nil {
+		return fmt.Errorf("parsing flags: %w", err)
+	}
+
+	const keyLength = 128 / 8
+	keyBytes := make([]byte, keyLength)
+
+	_, _ = rand.Read(keyBytes)
+
+	key := base58Encode(keyBytes)
+	fmt.Println(key)
+
+	return nil
+}
+
+func base58Encode(data []byte) string {
+	const alphabet = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
+	const radix = 58
+
+	zcount := 0
+	for zcount < len(data) && data[zcount] == 0 {
+		zcount++
+	}
+
+	// integer simplification of ceil(log(256)/log(58))
+	ceilLog256Div58 := (len(data)-zcount)*555/406 + 1 //nolint:gomnd
+	size := zcount + ceilLog256Div58
+
+	output := make([]byte, size)
+
+	high := size - 1
+	for _, b := range data {
+		i := size - 1
+		for carry := uint32(b); i > high || carry != 0; i-- {
+			carry += 256 * uint32(output[i]) //nolint:gomnd
+			output[i] = byte(carry % radix)
+			carry /= radix
+		}
+		high = i
+	}
+
+	// Determine the additional "zero-gap" in the output buffer
+	additionalZeroGapEnd := zcount
+	for additionalZeroGapEnd < size && output[additionalZeroGapEnd] == 0 {
+		additionalZeroGapEnd++
+	}
+
+	val := output[additionalZeroGapEnd-zcount:]
+	size = len(val)
+	for i := range val {
+		output[i] = alphabet[val[i]]
+	}
+
+	return string(output[:size])
+}