Add ShowMessageRequest API to psEditor

Right now we have the send message notifications hooked up, but there's also a request that looks like this:

It would be cool to have that hooked up in a generally accessible way. Right now you can do this:

using namespace OmniSharp.Extensions.LanguageServer.Protocol.Models
using namespace OmniSharp.Extensions.LanguageServer.Protocol.Server
using namespace OmniSharp.Extensions.LanguageServer.Server


# Type name is fully qualified because there's an ILanguageServer
# in both the Protocol and the Server namespaces.
$server = $psEditor.Components.GetService(
    [OmniSharp.Extensions.LanguageServer.Protocol.Server.ILanguageServer])

$task = [ShowMessageRequestExtensions]::Request(
    $server.Window,
    [ShowMessageRequestParams]@{
        Type = [MessageType]::Error
        Message = 'Question that is relevant to the options?'
        Actions = (
            [MessageActionItem]@{ Title = 'Option 1' },
            [MessageActionItem]@{ Title = 'Option 2' })
    })

while (-not $task.AsyncWaitHandle.WaitOne(200)) { }

# This will hold the chosen MessageActionItem
$result = $task.GetAwaiter().GetResult()

Something like this would be great though:

public partial class EditorWindow
{
    public string SendMessage(
        MessageType messageType,
        string caption,
        params string[] options);
}

Inizia con l’API EditorWindow di psEditor e segui la chiamata esistente a ShowMessageRequestExtensions attraverso ILanguageServer e il relativo servizio Window. Confronta la firma SendMessage richiesta con il supporto attuale per le notifiche e determina come debba essere esposto il MessageActionItem selezionato. Il lavoro è completo quando un’API EditorWindow generalmente accessibile può presentare le opzioni e restituire la scelta dell’utente.