Add a strongly typed layer for parts and elements

[twsouthwick]

This allows for decoupling the strongly-typed infrastructure more easily so that the underlying types don't need to know about the strongly typed information.

[twsouthwick]

@AlfredHellstern I'd like to get this into the next release. Do we have a milestone we're using to track that?

[twsouthwick]

@ThomasBarnekow I'd like your thoughts on this. I'm hoping by next release to be able to have the framework portion separated from the strongly typed stuff. This would enable things such as a "lightweight" deployment of just using OpenXmlElements and XLinq (or similar stuff when the full types aren't needed)

[AlfredHellstern]

@twsouthwick Next release should be towards the beginning of December, following the Nov 15 interop doc release.

[twsouthwick]

@AlfredHellstern I thought there was a release next week?

[AlfredHellstern]

yes, next week, to ship the content of the M365 aug22 PR#1196. I thought by "next" release you meant the one after the Aug release. Is your stuff ready to go into the Aug release?

[twsouthwick]

Yup. I'd like to get this in to verify a few things before splitting assemblies (hopefully the following release)

[ThomasBarnekow]

@ThomasBarnekow I'd like your thoughts on this. I'm hoping by next release to be able to have the framework portion separated from the strongly typed stuff. This would enable things such as a "lightweight" deployment of just using OpenXmlElements and XLinq (or similar stuff when the full types aren't needed)

@twsouthwick, I'll have a look. I can already say that I do like the idea!

[ThomasBarnekow]

@twsouthwick, I've had a look and this generally looks good to me. However, would you have some more information or examples of what this means for developers? How would we be using the SDK in the following cases:

1. Strongly Typed: Packages (e.g., WordprocessingDocument and strongly-typed classes only.
2. LINQ to XML (XLINQ): Packages and DocumentFormat.OpenXml.Linq only.
3. Combination: Packages and a combination of strongly-typed classes and DocumentFormat.OpenXml.Linq.

[twsouthwick]

This PR itself doesn't address that, but lays some foundation to enable that. This change gets things ready to be decoupled, while #1164 is what will enable the lightweight deployment. I want to verify that this structure doesn't break anything first by getting it into the release this week. Once that release is done, I'll probably merge #1164 into main and you can try things out.

[twsouthwick]

To answer the question in light of #1164:

Strongly Typed: Packages (e.g., WordprocessingDocument and strongly-typed classes only.

Nothing changes. The framework will be in a new package DocumentFormat.OpenXml.Framework that will be brought in transitively by referencing DocumentFormat.OpenXml

LINQ to XML (XLINQ): Packages and DocumentFormat.OpenXml.Linq only

Only need to reference DocumentFormat.OpenXml.Linq. Then, DocumentFormat.OpenXml.Framework will be brought in transitively.

Combination: Packages and a combination of strongly-typed classes and DocumentFormat.OpenXml.Linq.

Both DocumentFormat.OpenXml and DocumentFormat.OpenXml.Linq will be referenced and all three packages will be brought in.