Fix transparent sticky scroll background in the code peek panel

[nNoidea]

peekViewEditorStickyScroll.background uses the color of peekViewEditor.background and is also on top of it. peekViewEditor.background is an rgba color, which means that the sticky scroll features also becomes transparent and the text becomes unreadable when another text is underneath it.

peekViewEditor.background color seems like a normal rgb (without the alpha channel) color, but that's because the peek panel pushes away all the text underneath itself. The resulting color is the mix of peekViewEditor.background rgba and peekViewResult.background rgb values.

Since the sticky scroll feature always uses the color of the background of the panel it is in, this fix will take peekViewEditor.background and peekViewResult.background and mix them together into solid color and assign that color to the peekViewEditorStickyScroll.background to fix the issue.

Closes #361

Screenshots

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Merge checklist

• [x] Tested in GitHub Light Default theme

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[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: 09d42d0bc129b9c7ddad43de5ba9c79d5ec365c2

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
github-vscode-theme	Patch

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[nNoidea]

Did I mess up the PR progress? The problem is still in the latest version.