Respect inactive region column offsets when applying decorations

[Prashant Kumar Rai (8prashant)]

Summary

Fixes #12882

This change updates inactive-region decoration ranges to preserve the column offsets reported by the IntelliSense engine.

Previously, inactive regions were converted to whole-line VS Code ranges by forcing both start and end columns to 0. That caused lines containing active text before a preprocessor directive, such as a leading comment before #if 0, to be dimmed incorrectly.

The decoration range now uses startColumn and endColumn when they are present, while preserving the existing line-based fallback behavior for responses that do not include column data.

Changes

• Added optional startColumn and endColumn fields to InputRegion.
• Updated inactive-region decoration creation to use the reported start/end columns.
• Kept 0 as the fallback column value for compatibility with line-only inactive region data.

Testing

Tested locally on Windows.

• yarn compile
• yarn lint
• yarn test
• git diff --check

Also manually verified in an isolated Extension Development Host using a repro case where a comment precedes #if 0 on the same line. The comment remains active while the inactive block is dimmed.

[Copilot]

Pull request overview

Preserves IntelliSense-provided column offsets when rendering inactive regions.

Changes:

• Adds optional start/end columns to InputRegion.
• Uses column offsets with backward-compatible zero-column fallbacks.

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[Colen Garoutte-Carson (Colengms)]

Hi Prashant Kumar Rai (@8prashant) . Thanks for the contribution! The native component of the C/C++ Extension doesn't currently pass down startColumn and endColumn in InputRegion. I went ahead and made the corresponding changes to the native side. We can use this PR, if you'd like to remove the ? and undefined checks. (They will always be present, with my native-side changes). Or I could make the TypeScript-side adjustments myself in a new PR and you could abandon this one.

[Colen Garoutte-Carson (Colengms)]

Hi Prashant Kumar Rai (Prashant Kumar Rai (@8prashant)) . Thanks for the contribution! The native component of the C/C++ Extension doesn't currently pass down startColumn and endColumn in InputRegion. I went ahead and made the corresponding changes to the native side. We can use this PR, if you'd like to remove the ? and undefined checks. (They will always be present, with my native-side changes). Or I could make the TypeScript-side adjustments myself in a new PR and you could abandon this one.

Actually, I needed to make another minor change, so I created: #14667

We can abandon this PR. This change should make it into 1.34.0