Add error and warning colors for Hypercolor on VS Code

[sjarva]

What?
Add error and warning related colors to Hypercolor.

Why?
These colors have been added to Witch Hazel theme (in #20), so it would be good to have them for Hypercolor's users too.

Technical details
Find theme fitting hex colors for following VS Code UI parts, and add them to Witch Hazel-hypercolor-theme.json.

list.errorForeground
list.warningForeground
minimap.errorHighlight
minimap.warningHighlight
editorOverviewRuler.errorForeground
editorOverviewRuler.warningForeground
editorError.foreground
editorWarning.foreground
problemsErrorIcon.foreground
problemsWarningIcon.foreground

Provide screenshots of the UI with the new colors.