Generate EncodingMask encoding and decoding according to the current SDK release

[larws]

This fixes Issues #211 and #202

The dervied class with optional field(s) is now able to directly influence the creation of the encoding mask and it is guaranteed to happen at the beginning of the encoding and decoding.

Removed the invalid JSON encoding compatible methods for reading and writing an encoding mask since they were not correctly generated.

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✅ larws
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[opcfoundation-org]

Update ModelCompiler to use SDK 1.05.376. Please verify.

[larws]

It still generates invalid code in case of a complex data type with optional fields deriving from a data type without optional fields.

I think the current solution where the EncodingMask property is just a uint reduces the developer experience again, since the user is now forced to cast the generated flags herself. This could be avoided with the approach in this PR. If you agree with that I can incorporate the current changes to the master branch into the PR. If you don't think this is the right approach we can close the PR.

[opcfoundation-org]

The uint was used because casting was going to be needed if there was a subtype because the subtype declares a new enum with new fields.

The requirement to allow subtypes of StructureType=StructrureWithOptional field with the base type of StructureType=Structrure has been approved by the WG. It has not been implemented yet.

[larws]

That issue should be addressed by the proposed change, since every generated subtype introduces its own EncodingMask property with its specific fields type. And if I understand the code under (https://github.com/OPCFoundation/UA-ModelCompiler/blob/20dbd73ecdf59223030dc032d1a8a6b2d0cc5ec9/Opc.Ua.ModelCompiler/ModelGenerator2.cs#L3758-L3789)[ModelGenerator2.cs#L3758-L3789] correctly the fields enum should include all optional fields within the type hierarchy.

With the hooks OnWriteEncodingMask and OnReadEncodingMask the encoding mask should always be correctly written.