Use primary button color as accent color (#1859)

Author: sroy3

webview/src/shared/variables.scss

@@ -17,4 +17,4 @@ $header-border-color: var(--vscode-tree-tableColumnsBorder);
 $meta-cell-color: var(--vscode-descriptionForeground);
 
 $hover-background-color: var(--vscode-list-hoverBackground);
-$accent-color: var(--vscode-focusBorder);
+$accent-color: var(--button-primary-background);