DataGrid: Fix column reordering while using fixed columns (T1316881)

[Alyar666]

No description provided.

[Copilot]

Pull request overview

This PR fixes a bug in DataGrid column reordering when using fixed columns with virtual column rendering mode (T1316881). The fix removes incorrect column index offset adjustments that were causing reordering to malfunction.

Changes:

• Removed column index offset logic from drag-and-drop column reordering operations
• Updated keyboard navigation to handle column index offset corrections after scrolling
• Refactored column visibility index calculations to handle virtual rendering mode properly

Reviewed changes

Copilot reviewed 9 out of 12 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
m_headers_keyboard_navigation.ts	Added method to correct focused column index after scroll and simplified cell retrieval
m_column_keyboard_navigation_core.ts	Removed column index offset adjustments from visibility index calculations
m_columns_resizing_reordering.ts	Removed addColumnIndexOffset method and its usage from drag-and-drop operations
types.ts	Added type definitions for column index and drop location names
m_columns_controller_utils.ts	Refactored getColumnIndexByVisibleIndex to properly handle virtual rendering mode with column offsets
const.ts	Added constants for virtual command column and headers location
visual.ts	Added visual regression tests for column reordering scenarios
functional.ts	Added functional tests for column reordering with fixed columns and virtual rendering
columnReordering.ts	Moved existing tests to separate functional.ts and visual.ts files

[Copilot]

Pull request overview

Copilot reviewed 9 out of 12 changed files in this pull request and generated 2 comments.

[Copilot]

The filter condition compares column.type with col.type, but should compare the constant GROUP_COMMAND_COLUMN_NAME with col.type directly. The current logic will always match the first column with the same type, which might not be the intended behavior.

Suggested change

	return that._columns.filter((col) => column.type === col.type)[0] || column;
	return that._columns.filter((col) => col.type === GROUP_COMMAND_COLUMN_NAME)[0] || column;

[Copilot]

The use of optional chaining with nullish coalescing could mask issues where column is unexpectedly undefined. Consider using isDefined(column?.index) check consistent with the codebase pattern, or add explicit validation.

Suggested change

	return column?.index ?? -1;
	const columnIndex = column?.index;
	return isDefined(columnIndex) ? columnIndex : -1;