list commands always output JSON; add CliJsonSerializerContext + SnowflakeJsonConverter in CLI

Agent-Logs-Url: https://github.com/Tyrrrz/DiscordChatExporter/sessions/58698f45-e22e-4bd4-aec4-31f801051467

Co-authored-by: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>

DiscordChatExporter.Cli/Utils/Json/CliJsonSerializerContext.cs

@@ -0,0 +1,26 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using DiscordChatExporter.Core.Discord.Data;
+
+namespace DiscordChatExporter.Cli.Utils.Json;
+
+[JsonSourceGenerationOptions(
+    PropertyNamingPolicy = JsonKnownNamingPolicy.CamelCase,
+    GenerationMode = JsonSourceGenerationMode.Metadata
+)]
+[JsonSerializable(typeof(Channel[]))]
+[JsonSerializable(typeof(Guild[]))]
+internal partial class CliJsonSerializerContext : JsonSerializerContext
+{
+    // Instance pre-configured with converters for Snowflake (serialised as a string)
+    // and all enum types (serialised as their name).  Defined here so the Core types
+    // are never touched.
+    public static CliJsonSerializerContext Instance { get; } =
+        new(
+            new JsonSerializerOptions
+            {
+                PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
+                Converters = { new SnowflakeJsonConverter(), new JsonStringEnumConverter() },
+            }
+        );
+}

DiscordChatExporter.Cli/Utils/Json/SnowflakeJsonConverter.cs

@@ -0,0 +1,21 @@
+using System;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using DiscordChatExporter.Core.Discord;
+
+namespace DiscordChatExporter.Cli.Utils.Json;
+
+internal class SnowflakeJsonConverter : JsonConverter<Snowflake>
+{
+    public override Snowflake Read(
+        ref Utf8JsonReader reader,
+        Type typeToConvert,
+        JsonSerializerOptions options
+    ) => Snowflake.Parse(reader.GetString()!);
+
+    public override void Write(
+        Utf8JsonWriter writer,
+        Snowflake value,
+        JsonSerializerOptions options
+    ) => writer.WriteStringValue(value.ToString());
+}