Add GDI+ printing extensions to CADability.Forms (#412)

[dsn27]

Part of #412 (step 7, printing). Stacked on #474; retarget to master once #474 is merged.

Why

#412 now requires that every class member removed in 2.0 is [Obsolete] in 1.x naming its replacement. #474 marked LayoutView.Print, GDI2DView.PrintSinglePage and PrintToGDI obsolete, but their replacement did not exist yet, so the messages only said "moves into CADability.Forms in 2.0".

What

• New CADability.Forms.GdiPrinting with extension methods:
  • PrintDocument.Print(LayoutView) replaces LayoutView.Print(PrintDocument)
  • PrintDocument.PrintSinglePage(GDI2DView) replaces GDI2DView.PrintSinglePage(PrintDocument)
  • PrintDocument.PrintSinglePage(Project, string, bool) replaces PrintToGDI.PrintSinglePage(...)
  • Bitmap.DrawModel(Model, Projection, Layer[], bool, bool) replaces new PrintToGDI(bitmap).PrintToBitmap(...)
• The three [Obsolete] messages now name these replacements.
• In 1.x the extensions forward to the kernel implementation. It moves into CADability.Forms in 2.0 (step 8).
• tests/GdiPrintingTests.cs (Windows only) checks that DrawModel renders pixel for pixel like PrintToGDI.PrintToBitmap, and that the line is actually drawn.

Design notes

• Receiver. The receiver is the PrintDocument or the Bitmap, not the view. An extension LayoutView.Print(PrintDocument) would be hidden by the instance method of the same name until 2.0, so callers could not switch to it.
• No public PrintToGDI class in Forms in 1.x. A class with the same name in CADability.Forms would make PrintToGDI ambiguous for code that has both using CADability; and using CADability.Forms;, which is a source break. The class itself moves in 2.0.

Deviations from the list in #412

• No public interface is changed. IUIService.ShowPageSetupDlg/ShowPrintDlg keep their [Obsolete] from Save page settings as a neutral PageSetup (#412, step 7b) #474; they are interface members, which the "name the replacement" rule for class members does not cover.
• PrintToGDI.LineWidthFactor and PrintToGDI.OnPrintPage get no extension of their own. In this repository only the kernel uses them, and the obsolete message on the class covers them. DontRecalcTriangulation is a member of IPaintTo3D and stays.

Testing

• CADability.Forms builds.
• CADability.Tests on Linux: 621 passed, 21 skipped, 0 failed.
• The test project compiles for net8.0-windows (-p:OS=Windows_NT). The Windows test itself runs on the Windows job of the integration branch ([Draft, do not merge] Integration branch for #412 #467).

🤖 Generated with Claude Code

https://claude.ai/code/session_01YXvDW91oXpy7RquGHNxgR5

[dsn27]

Closing without merge. The printing extensions only existed to give the [Obsolete] printing members a named replacement for step 8 of #412, which is now deferred. The browser does not need printing to move (#484). Printing stays where it is in 1.x.

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