[API Proposal]: DateTime/DateTimeOffset format

Background and motivation

There is currently formats related to DateTime:

"yyyy-MM-ddTHH:mm:ss.fffZ"; "yyyy-MM-ddTHH:mm:ssZ"

and DateTimeOffset:

"yyyy-MM-ddTHH:mm:ss.fffK"; "yyyy-MM-ddTHH:mm:ssK"

These look related to ISO 8601. See the roundtrip format in:

https://learn.microsoft.com/en-us/dotnet/standard/base-types/standard-date-and-time-format-strings

And the page on the standard on wikipedia:
https://en.wikipedia.org/wiki/ISO_8601

API Proposal

Modules in the Extensions.InvariantCulture namespace named DateTime and DateTimeOffset with related functions. Move the implementation of TryParse and Parse of DateTime and DateTimeOffset to these modules.

namespace FSharpPlus.Extensions.InvariantCulture

[<RequireQualifiedAccess>]
module DateTime =
     let tryParse (x:string) =
        match DateTime.TryParseExact (x, [|"yyyy-MM-ddTHH:mm:ss.fffZ"; "yyyy-MM-ddTHH:mm:ssZ"|], null, DateTimeStyles.RoundtripKind) with
        | true, x -> Some x
        | _ ->
            match DateTime.TryParse (x, CultureInfo.InvariantCulture, DateTimeStyles.AdjustToUniversal) with
            | true, x -> Some x
            | _ -> None

API Usage

open FSharpPlus.Extensions
let parsed = InvariantCulture.DateTime.tryParse stringFromTheInternet

Alternative Designs

No response

Risks

Probably little risk

Are you willing to help with a proof-of-concept (as PR in that or a separate repo) first and as pull-request later on?

Yes, please assign this issue to me.

The issue names no files or tests. Start by locating the existing DateTime and DateTimeOffset TryParse and Parse implementations, then compare their current formats with the proposed InvariantCulture modules. Done means the API shape and parsing behavior for both types are agreed and implemented, with validation of the proposed formats.