Add min-size attributes to `<vscode-split-layout>`

[dankeboy36]

Please add first-class support for minimum pane sizes on <vscode-split-layout> to prevent the start or end pane from collapsing to 0 when users drag the sash.

split-layout-min-size.mov

Desired behavior

• Accept attributes like min-start="240px" or min-end="25%".
• Clamp sash movement so the start pane never drops below min-start and the end pane never drops below min-end.
• Same logic when setting handlePosition programmatically.

This would let lock master/detail panes to a reasonable size without hacky event listeners or CSS overrides.

Thank you!

[bendera]

@lucifer-yf I wanted to publish it at the weekend but I didn't have enough time. Until then I suggest to linking the pacckage.