Add SlashCommandIgnoreAttribute for hiding enum values from slash commands

[Zont1k]

Description

Adds a new attribute that can be applied to enum fields to exclude them from being shown as options in slash commands.

Closes #330

Changes

• Added in
• Modified to filter out fields with the attribute
• Added unit test

Usage

public enum MyEnum
{
    Value1,
    [SlashCommandIgnore]
    None = 0,  // Will not be shown in slash commands
    Value2,
}

Note

The project requires .NET SDK 10.0.301 for source generators which is not available in my local environment, so I was unable to run the full test suite. However, the logic is straightforward and follows the existing pattern used by .

[github-actions]

The documentation preview is available at https://preview.netcord.dev/388.

[KubaZ2]

I think this attribute should be named SlashCommandChoiceIgnoreAttribute. SlashCommandIgnoreAttribute is misleading.

[KubaZ2]

Suggested change

	var filteredFields = fields.Where(f => f.GetCustomAttribute<SlashCommandIgnoreAttribute>() is null).ToArray();
	var count = filteredFields.Length;
	var choices = new ApplicationCommandOptionChoiceProperties[count];
	for (var i = 0; i < count; i++)
	choices[i] = await CreateChoiceAsync(fields[i]).ConfigureAwait(false);
	choices[i] = await CreateChoiceAsync(filteredFields[i]).ConfigureAwait(false);
	var ignoreAttributeType = typeof(SlashCommandIgnoreAttribute);
	var count = fields.Length;
	List<ApplicationCommandOptionChoiceProperties> choices = new(count);
	for (var i = 0; i < count; i++)
	{
	var field = fields[i];
	if (!field.IsDefined(ignoreAttributeType))
	choices.Add(await CreateChoiceAsync(field).ConfigureAwait(false));
	}