Remove IComparisonOperators<TSelf, TSelf, bool> and IParsable<TSelf> from the IQuantity interface

[lipchev]

Here is the current declaration:

    /// <summary>
    ///     An <see cref="IQuantity{TUnitType}"/> that (in .NET 7+) implements generic math interfaces for equality, comparison and parsing.
    /// </summary>
    /// <typeparam name="TSelf">The type itself, for the CRT pattern.</typeparam>
    /// <typeparam name="TUnitType">The underlying unit enum type.</typeparam>
#if NET7_0_OR_GREATER
    public interface IQuantity<TSelf, TUnitType>
        : IQuantity<TUnitType>
        , IComparisonOperators<TSelf, TSelf, bool>
        , IParsable<TSelf>
#else
    public interface IQuantity<in TSelf, TUnitType>
        : IQuantity<TUnitType>
#endif
        where TSelf : IQuantity<TSelf, TUnitType>
        where TUnitType : Enum

I think that the IComparisonOperators<TSelf, TSelf, bool> and IParsable<TSelf> declarations should be moved to the implementation section.

The motivation: reduce the number of methods / operators required for the "custom quantities": consider how many methods are added by moving HowMuch from : IQuantity to : IQuantity<HowMuch, HowMuchUnit>.

A more theoretical motivation is that by having it on the interface, it feels like we're expressing a requirement, as in "I need this method in order to be able to do something"- which is clearly not the case here.
IMO anyone requiring the generic constraint can use a combination of constraints:

public List<TQuantity> ParseQuantities<TQuantity>(string text) where TQuantity: IParsable<TQuantity>;
public List<TUnit> ParseUnits<TQuantity, TUnit>(string text) where TQuantity: IQuantity<TUnit>, IParsable<TQuantity>;

Note that repeating the declaration 180 times would add few KB to the size, but if that's a priority, we could introduce some IDefaultQuantity<TQuantity> interface and move all interface declarations that are shared by all quantities:

#if NET7_0_OR_GREATER
        IComparisonOperators<TSelf, TSelf, bool>,
        IParsable<TSelf>,
#endif
        IComparable,
        IComparable<TSelf>,
        IConvertible,
        IEquatable<TSelf>,
        IFormattable

[lipchev]

Note that repeating the declaration 180 times would add few KB to the size, but if that's a priority, we could introduce some IDefaultQuantity<TQuantity> interface and move all interface declarations that are shared by all quantities:

Hmm, weirdly enough, after removing it from the interface there was actually a decrease in size (~1KB).. (🤷 )

[angularsen]

Yeah that makes sense I think, moving interfaces to implementations instead of requiring all IQuantity implementors to add all the same stuff. As long as there isn't some IQuantity-based code that expects this or that, you will find out soone enough I guess 😄

[lipchev]

Fixed by #1459