Set default ruler width (#205)

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be closed until separated. -->

### Description

Adds a minimum ruler width equal to 4 digits wide to reduce layout shift
while scrolling.

### Related Issues

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<!--- If this PR resolves the issue please specify (e.g. * closes #123)
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<!--- If this PR addresses multiple issues, these issues must be related
to one other -->

* N/A, discussed a couple times in discord.

### Checklist

<!--- Add things that are not yet implemented above -->

- [x] I read and understood the [contributing
guide](https://github.com/CodeEditApp/CodeEdit/blob/main/CONTRIBUTING.md)
as well as the [code of
conduct](https://github.com/CodeEditApp/CodeEdit/blob/main/CODE_OF_CONDUCT.md)
- [x] The issues this PR addresses are related to each other
- [x] My changes generate no new warnings
- [x] My code builds and runs on my machine
- [x] My changes are all related to the related issue above
- [x] I documented my code

### Screenshots

Previous:
<img width="356" alt="Screenshot 2023-07-11 at 12 28 26 PM"
src="https://github.com/CodeEditApp/CodeEditTextView/assets/35942988/469044fa-189f-41d8-83ca-367f2244fe82">

Now:
<img width="321" alt="Screenshot 2023-07-11 at 12 27 51 PM"
src="https://github.com/CodeEditApp/CodeEditTextView/assets/35942988/547dcdda-f50e-4be6-a065-7fef5b6e7cd7">

Author: thecoolwinter

Package.resolved

@@ -207,9 +207,15 @@ public class STTextViewController: NSViewController, STTextViewDelegate, ThemeAt
             : NSColor.selectedTextBackgroundColor.withSystemEffect(.disabled)
         rulerView.baselineOffset = baselineOffset
         rulerView.highlightSelectedLine = isEditable
-        rulerView.rulerInsets = STRulerInsets(leading: rulerFont.pointSize * 1.6, trailing: 8)
+        rulerView.rulerInsets = STRulerInsets(leading: 12, trailing: 8)
         rulerView.font = rulerFont
         rulerView.backgroundColor = theme.background
+        rulerView.ruleThickness = max(
+            NSString(string: "1000").size(withAttributes: [.font: rulerFont]).width
+            + rulerView.rulerInsets.leading
+            + rulerView.rulerInsets.trailing,
+            rulerView.ruleThickness
+        )
         if self.isEditable == false {
             rulerView.selectedLineTextColor = nil
             rulerView.selectedLineHighlightColor = .clear