update for breaking blueprintjs style changes

it is no longer feasible to build the blueprintjs css ourselves, so we
just use all of the default variable values and override things using
selectors instead.

src/utils/external-link.scss

@@ -1,13 +1,13 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2021 The Pybricks Authors
+// Copyright (c) 2021-2022 The Pybricks Authors
 
-@import '../variables.scss';
+@use '@blueprintjs/core/lib/scss/variables' as bp;
 
 span.pb-external-link {
     white-space: nowrap;
 }
 
 // override some button magic in case this is used in a button
-.#{$ns}-button .pb-external-link .#{$ns}-icon:first-child:last-child {
+.#{bp.$ns}-button .pb-external-link .#{bp.$ns}-icon:first-child:last-child {
     margin: 0;
 }

src/utils/tree-renderer.scss

@@ -1,11 +0,0 @@
-// SPDX-License-Identifier: MIT
-// Copyright (c) 2022 The Pybricks Authors
-
-@import '../variables.scss';
-
-// HACK: work around https://github.com/palantir/blueprint/issues/5229
-// TODO: this can be removed when https://github.com/palantir/blueprint/pull/5235 is merged and released
-
-.#{$ns}-focus-disabled .pb-focus-manager-ignore :focus {
-    outline: $pt-outline-color auto 2px !important;
-}

src/utils/tree-renderer.tsx

@@ -6,7 +6,6 @@
 // based on https://github.com/lukasbach/react-complex-tree/blob/239fb0c5f49f3c24e307142fb3d7e828440c3f55/packages/blueprintjs-renderers/src/renderers.tsx
 // Copyright (c) 2021 Lukas Bach
 
-import './tree-renderer.scss';
 import {
     Button,
     Classes,
@@ -44,7 +43,7 @@ export const renderers: Omit<
 > = {
     renderTreeContainer: (props) => (
         <div
-            className={cx(Classes.TREE, 'pb-focus-manager-ignore')}
+            className={cx(Classes.TREE, Classes.FOCUS_STYLE_MANAGER_IGNORE)}
             {...props.containerProps}
         >
             {props.children}