Handle C# 14 field keyword

[bjornhellander]

See https://learn.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-14#the-field-keyword

Investigate needed changes (including just adding tests for cases that already work as expected).

[bjornhellander]

No current problems found.

SA1000KeywordsMustBeSpacedCorrectly: Add test to verify that this analyzer ignores this new keyword
SA1003SymbolsMustBeSpacedCorrectly: Add test to verify that a space is expected in e.g. field + field
SA1008OpeningParenthesisMustBeSpacedCorrectly: add test to verify that no space is expected in field(9)
SA1010OpeningSquareBracketsMustBeSpacedCorrectly: Add test to verify that no space is expected in field[0] and [ field ];
SA1019MemberAccessSymbolsMustBeSpacedCorrectly: Add test to verify that no space is expected in field.X
SA1020IncrementDecrementSymbolsMustBeSpacedCorrectly: Add test to verify that no space is expected in field++ or ++field
SA1021NegativeSignsMustBeSpacedCorrectly: Add to verify that no space is expected in -field
SA1022PositiveSignsMustBeSpacedCorrectly: Add to verify that no space is expected in +field
SA1023DereferenceAndAccessOfSymbolsMustBeSpacedCorrectly: Add test to verify that no space is expected in *field
SA1024ColonsMustBeSpacedCorrectly: Add test to verify that spaces are expected in x ? field : field

Many of these are weird cases, but should be handled anyway.

[x3rt]

No current problems found.

I have found 1 problem.

Previously only auto-implemented properties were able to have initializers, but now properties that use the new field keyword can also have initializers.

Due to this the following example reports:

SA1500: Braces for multi-line statements should not share line
SA1513: Closing brace should be followed by blank line

crude example but it gets the point across

/// <summary>
/// Gets an example object.
/// </summary>
public object Example
{
    get
    {
        if (field == null)
        {
            field = new object();
        }

        return field;
    }
} = null!;

Seems like StyleCop prefers it to be formatted like so:

/// <summary>
/// Gets an example object.
/// </summary>
public object Example
{
    get
    {
        if (field == null)
        {
            field = new object();
        }

        return field;
    }
}

= null!;

which seems unintentional. Furthermore it seems to allow anything as long as there is 1 blank line between the definition and the initializer. For example it sees the following as breaking no rules:

    /// <summary>
    /// Gets an example object.
    /// </summary>
    public object Example
    {
        get
        {
            if (field == null)
            {
                field = new object();
            }

            return field;
        }
    }

                                                                                                        = null!;

[bjornhellander]

@x3rt Excellent catch! Thank you!

[bjornhellander]

Problem in SA1500 and SA1513 fixed. Tests remain.