[Feature] Modal Select Components Support for IF

[Cenngo]

This PR adds support for UserSelect, RoleSelect, ChannelSelect, MentionableSelect and SelectMenu to Interaction Framework.

At the moment this PR is a draft and stuff like declaratively defining SelectMenu options needs to be added. However the in the current state of this PR the following has been added. Contents of this PR is subject to change depending on #3172 and isn't functional currently.

To make modal generation/response flow more modular and make granular control possible, a new TypeConverter type called ModalComponentTypeConverter has been introduced. The new TypeConverter exposes a WriteAsync<>() method to allow the alteration of input component parameters when a RespondWithModal<>() extension method is called. 5 default TypeConverters are included in this PR for the following types: Array, Snowflake entity, Enum, IConvertible, Nullable.
With the default setup, User/Channel/Role/Mentionable select value can be automatically mapped to single IUser/IRole/IChannel entities if a single-select is used, to IUser[]/IRole[]/IChannel[] arrays if a multi-select is used. For SelectMenu components, just like with message component SelectMenus, the converter falls back to a TypeReader for converting the returned string values to the underlying CLR type. Enums can be used to auto-populate SelectMenu options and returned values can be mapped to regular enums if a single-select is used, to flags enums if a multi-select is used. [HideAttribute] used for SlashCommand parameters, can be used to hide select enum values,
and a new [SelectMenuOptionAttribute] can be used to define description, emote, and IsDefault values for individul enum values. Nullable types can be used which use the ModalComponentTypeConverter assigned to the underlying type for convertion. And finally, TextInput and single-select menu values can be converted to IConvertible types. Instance values of the component properties are used to supply the default values of components.