Implement "Move Editor to Start" command in editor title context menu

[kheif]

What this PR does

This pull request adds a new command called "Move Editor to Start", which allows users to move the selected editor tab to the beginning of its group.

The command can be accessed via the editor title context menu. This helps users reorganize their open editors more efficiently, especially in workflows involving multiple open files.

Why it matters

Currently, VS Code does not provide a quick way to move an editor tab directly to the beginning of the group without dragging or using shortcut. This feature improves usability and accessibility.

Related Issue

This PR is related to the issue #250054, which discusses the need for a command to move editor tabs directly to the start of their group.

[kheif]

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