💥🐛Change DataMember ordering to 1-indexed (#1360)

Related #1200 
Fixes #1356

Apparently, protobuf-net does not support 0-indexed order values.

### Changes
- Change `DataMember` explicit order from 0-indexed to 1-indexed

### Background
Some investigation indicates that the actual order value is not important, only the relative ordering: 
#1356 (comment)

- WCF should tolerate this, according to its docs. #1356 (comment)
- Binary formatters hopefully only care about relative ordering and thus still compatible?
	- Protobuf-net, it never worked and should be OK
	- [BinaryFormatter](https://learn.microsoft.com/en-us/dotnet/api/system.runtime.serialization.formatters.binary.binaryformatter?view=net-8.0) is obsolete and generally not recommended for years, so hopefully no users are affected
	- A bunch of others exist too, haven't looked into how they handle this
- XML/JSON serializers should tolerate any order, can't imagine it breaking these?

CodeGen/Generators/UnitsNetGen/QuantityGenerator.cs

@@ -99,7 +99,7 @@ namespace UnitsNet
  Writer.WL(@$"
 #endif");
  }
- 
+
  if (_quantity.ValueType == "decimal") Writer.WL(@$"
  IDecimalQuantity,");
 
@@ -115,13 +115,13 @@ namespace UnitsNet
  /// <summary>
  /// The numeric value this quantity was constructed with.
  /// </summary>
- [DataMember(Name = ""Value"", Order = 0)]
+ [DataMember(Name = ""Value"", Order = 1)]
  private readonly {_quantity.ValueType} _value;
 
  /// <summary>
  /// The unit this quantity was constructed with.
  /// </summary>
- [DataMember(Name = ""Unit"", Order = 1)]
+ [DataMember(Name = ""Unit"", Order = 2)]
  private readonly {_unitEnumName}? _unit;
 ");
  GenerateStaticConstructor();
@@ -759,41 +759,41 @@ private void GenerateRelationalOperators()
  {
  leftConversionProperty = "Total" + leftConversionProperty;
  }
- 
+
  if (relation.RightQuantity.Name is nameof(TimeSpan))
  {
  rightConversionProperty = "Total" + rightConversionProperty;
  }
- 
+
  if (leftParameter == rightParameter)
  {
  leftParameter = "left";
  rightParameter = "right";
  }
- 
+
  var leftPart = $"{leftParameter}.{leftConversionProperty}";
  var rightPart = $"{rightParameter}.{rightConversionProperty}";
- 
+
  if (leftParameter is "double")
  {
  leftParameter = leftPart = "value";
- } 
- 
+ }
+
  if (rightParameter is "double")
  {
  rightParameter = rightPart = "value";
  }
- 
+
  var leftCast = relation.LeftQuantity.ValueType is "decimal" ? "(double)" : string.Empty;
  var rightCast = relation.RightQuantity.ValueType is "decimal" ? "(double)" : string.Empty;
- 
+
  var expression = $"{leftCast}{leftPart} {relation.Operator} {rightCast}{rightPart}";
 
  if (relation.ResultQuantity.Name is not ("double" or "decimal"))
  {
  expression = $"{relation.ResultQuantity.Name}.From{relation.ResultUnit.PluralName}({expression})";
  }
- 
+
  Writer.WL($@"
  /// <summary>Get <see cref=""{relation.ResultQuantity.Name}""/> from <see cref=""{relation.LeftQuantity.Name}""/> {relation.Operator} <see cref=""{relation.RightQuantity.Name}""/>.</summary>
  public static {relation.ResultQuantity.Name} operator {relation.Operator}({relation.LeftQuantity.Name} {leftParameter}, {relation.RightQuantity.Name} {rightParameter})