Added WinRT attribute to Columns

[licon4812]

This pull request adds the [WinRT.GeneratedBindableCustomProperty] attribute to several TableView column classes to improve WinRT binding support on Windows platforms. Additionally, it changes the affected classes from non-partial to partial where appropriate, enabling further extensibility and compatibility with code generation tools.

I did this to ensure that if columns are auto generated, WinRT bindings work correctly.

WinRT binding support enhancements:

• Added [WinRT.GeneratedBindableCustomProperty] attribute to all TableView column classes, gated behind the WINDOWS conditional compilation directive. This ensures custom property generation for WinRT bindings only on Windows. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10]

Class definition changes for extensibility:

• Changed all affected column classes (TableViewCheckBoxColumn, TableViewComboBoxColumn, TableViewDateColumn, TableViewNumberColumn, TableViewTemplateColumn, TableViewTextColumn, TableViewTimeColumn, TableViewToggleSwitchColumn) to be partial classes, allowing for future extensions and compatibility with code generation. [1] [2] [3] [4] [5] [6] [7] [8]

Base class updates:

• Updated the abstract base classes TableViewBoundColumn and TableViewColumn to include the new attribute and, for TableViewColumn, to be partial as well. [1] [2]

[Copilot]

Pull Request Overview

This PR adds WinRT binding support for TableView column classes by applying the [WinRT.GeneratedBindableCustomProperty] attribute to all column types, enabling proper custom property generation for WinRT bindings on Windows platforms.

• Adds conditional [WinRT.GeneratedBindableCustomProperty] attribute to all TableView column classes (gated behind WINDOWS compilation directive)
• Changes affected column classes from non-partial to partial to enable extensibility and code generation compatibility
• Updates both concrete column implementations and abstract base classes for consistent WinRT support

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
TableViewBoundColumn.cs	Added WinRT attribute to abstract base class for bound columns
TableViewColumn.cs	Added WinRT attribute and made abstract base class partial
TableViewCheckBoxColumn.cs	Added WinRT attribute and made class partial
TableViewComboBoxColumn.cs	Added WinRT attribute and made class partial
TableViewDateColumn.cs	Added WinRT attribute (class already partial)
TableViewNumberColumn.cs	Added WinRT attribute and made class partial
TableViewTemplateColumn.cs	Added WinRT attribute and made class partial
TableViewTextColumn.cs	Added WinRT attribute and made class partial
TableViewTimeColumn.cs	Added WinRT attribute (class already partial)
TableViewToggleSwitchColumn.cs	Added WinRT attribute and made class partial

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