Move internal packages to an internal folder

For reference: https://go.dev/doc/go1.4#internalpackages

config/parser_test.go

@@ -1,60 +0,0 @@
-// SPDX-FileCopyrightText: Copyright The Miniflux Authors. All rights reserved.
-// SPDX-License-Identifier: Apache-2.0
-
-package config // import "miniflux.app/v2/config"
-
-import (
-	"testing"
-)
-
-func TestParseBoolValue(t *testing.T) {
-	scenarios := map[string]bool{
-		"":        true,
-		"1":       true,
-		"Yes":     true,
-		"yes":     true,
-		"True":    true,
-		"true":    true,
-		"on":      true,
-		"false":   false,
-		"off":     false,
-		"invalid": false,
-	}
-
-	for input, expected := range scenarios {
-		result := parseBool(input, true)
-		if result != expected {
-			t.Errorf(`Unexpected result for %q, got %v instead of %v`, input, result, expected)
-		}
-	}
-}
-
-func TestParseStringValueWithUnsetVariable(t *testing.T) {
-	if parseString("", "defaultValue") != "defaultValue" {
-		t.Errorf(`Unset variables should returns the default value`)
-	}
-}
-
-func TestParseStringValue(t *testing.T) {
-	if parseString("test", "defaultValue") != "test" {
-		t.Errorf(`Defined variables should returns the specified value`)
-	}
-}
-
-func TestParseIntValueWithUnsetVariable(t *testing.T) {
-	if parseInt("", 42) != 42 {
-		t.Errorf(`Unset variables should returns the default value`)
-	}
-}
-
-func TestParseIntValueWithInvalidInput(t *testing.T) {
-	if parseInt("invalid integer", 42) != 42 {
-		t.Errorf(`Invalid integer should returns the default value`)
-	}
-}
-
-func TestParseIntValue(t *testing.T) {
-	if parseInt("2018", 42) != 2018 {
-		t.Errorf(`Defined variables should returns the specified value`)
-	}
-}