Fix whitespace

private readonly string[] _commonTags = { "<i>", "<b>", "<u>", "<font " };

        private string FixDigitOrLetterAdjacentToTag(string text)
        {
            // foo<i>bar => foo <i>bar | foo<i><b>bar => foo <i><b>bar
            foreach (var commonTag in _commonTags)
            {
                var firstTagIndex = text.IndexOf(commonTag, StringComparison.Ordinal);
                if (firstTagIndex < 1)
                {
                    continue;
                }

                // add chars you want to match e.g: ], )
                if (char.IsLetterOrDigit(text[firstTagIndex - 1]) && IsLetterOrDigitAfterTag(text, firstTagIndex + commonTag.Length))
                {
                    text = text.Insert(firstTagIndex, " ");
                }
            }

            return text;

            bool IsLetterOrDigitAfterTag(string s, int index)
            {
                if (index == s.Length)
                {
                    return false;
                }

                var ch = s[index];
                if (char.IsLetterOrDigit(ch))
                {
                    return true;
                }

                foreach (var tag in _commonTags)
                {
                    // we are expecting the tag + 1 char/letter
                    if (index + tag.Length + 1 >= s.Length)
                    {
                        continue;
                    }

                    var tagIndex = text.IndexOf(tag, index, StringComparison.Ordinal);
                    if (tagIndex != index)
                    {
                        continue;
                    }

                    return IsLetterOrDigitAfterTag(text, tagIndex + tag.Length);
                }

                return false;
            }
        }


// https://github.com/SubtitleEdit/subtitleedit/issues/5110