Fix MA0139 false positive when the Serilog params array is passed as an array

[meziantou]

What

For the Serilog methods (Log.Information(string messageTemplate, params object?[]? propertyValues), ...), the values were read from the params array only when the call used the expanded form. When the array was passed directly (normal form), the call fell through to the fallback that uses each argument as a value, so the whole object[] was checked against the first placeholder:

// LoggerParameterTypes.txt: Prop;System.Int32
Log.Information("{Prop}", new object[] { 1 });
// MA0139: Log parameter 'Prop' must be of type 'global::System.Int32' but is of type 'global::System.Object[]'

Fix

When the argument after the template is bound to the params parameter, the values are the elements of the array creation, whether the call is in the expanded or in the normal form (implicit conversions are unwrapped). When the array is not created in the call (a variable, a method call, null...), its values are unknown, so no value is checked and only the placeholder names are validated, as when fewer values than placeholders are passed.

The generic overloads (Information<T>(string, T)) are unchanged: when they are selected, such as for new string[] { "" }, the array is a single property value.

Tests

Added SeriLog_Log_Information_ParamsArrayInNormalForm (valid and invalid element in new object[] { ... }) and SeriLog_Log_Information_ParamsArrayVariable. Both failed before the fix.

Ran the LoggerParameterTypeAnalyzer tests (MA0124 and MA0139) on roslyn5.9 and roslyn4.8 (63/63 passing on both).