refactor: change DefaultQuantities to use property initializer

[angularsen]

Fixup of #1555

[lipchev]

I believe there was a reason for this- if we use an eager initializer here, we couldn't allow for re-configuring the "default".
Also note, that you're editing the generated file.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93%. Comparing base (5131d24) to head (abcdb72).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@          Coverage Diff           @@
##           master   #1575   +/-   ##
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  Coverage      93%     93%           
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  Files         311     311           
  Lines       28781   28781           
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  Hits        26864   26864           
  Misses       1917    1917           

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[angularsen]

Right, but I thought the idea was that this is the built-in provider. Any customizations happen further out, such as in MassInfo.CreateDefault(Func customizeUnits): #1555 (review) or by manipulating UnitsNetSetup.Default.

[lipchev]

The Mass.Info is currently read-only- in the other project I end up doing something like:

        /// <summary>
        ///     Configures a custom quantity for the default configuration.
        /// </summary>
        /// <typeparam name="TQuantity">The type of the quantity to configure.</typeparam>
        /// <typeparam name="TUnit">The type of the unit associated with the quantity, which must be an enumeration.</typeparam>
        /// <param name="createCustomConfigurationDelegate">
        ///     A delegate that creates a custom configuration for the quantity.
        /// </param>
        /// <returns>The current instance of <see cref="UnitsNet.UnitsNetSetup.DefaultConfigurationBuilder" /> for method chaining.</returns>
        public DefaultConfigurationBuilder ConfigureQuantity<TQuantity, TUnit>(Func<QuantityInfo<TQuantity, TUnit>> createCustomConfigurationDelegate)
            where TQuantity : IQuantity<TQuantity, TUnit>
            where TUnit : struct, Enum
        {
            _quantitiesSelector ??= new QuantitiesSelector(() => Quantity.DefaultProvider.Quantities);
            _quantitiesSelector.Configure(createCustomConfigurationDelegate);
            return this;
        }

so for a particular quantity we can override the default setter, by constructing it using the provided customization function. The action using the Quantity.Provider would end up constructing the QuantityInfo's before we are able to do anything.

[lipchev]

I've merged #1576