Feature request: Add ToLowerInvariantStringFast() and ToUpperInvariantStringFast()

[rmja]

Example implementation could be something like:

        private static class LowerInvariant
        {
            public static readonly string Minute = nameof(Minute).ToLowerInvariant();
            public static readonly string Hour = nameof(Hour).ToLowerInvariant();
            public static readonly string Day = nameof(Day).ToLowerInvariant();
            public static readonly string Week = nameof(Week).ToLowerInvariant();
            public static readonly string Month = nameof(Month).ToLowerInvariant();
            public static readonly string Year = nameof(Year).ToLowerInvariant();
        }

        public static string ToLowerInvariantStringFast(this Period value)
            => value switch
            {
                Period.Minute => LowerInvariant.Minute,
                Period.Hour => LowerInvariant.Hour,
                Period.Day => LowerInvariant.Day,
                Period.Week => LowerInvariant.Week,
                Period.Month => LowerInvariant.Month,
                Period.Year => LowerInvariant.Year,
                _ => value.ToStringFast().ToLowerInvariant(),
            };

This would allow for zero allocation conversions to lower string instead of Period.Hour.ToStringFast().ToLowerInvariant().

Same idea goes for ToUpperInvariantStringFast().

[dylanvdmerwe]

Great idea.