Modify checkboxes so that they can be indeterminate

To add the third state, we create our own checkboxes using font awesome
icons.

scm-ui/ui-components/src/forms/TriStateCheckbox.tsx

@@ -0,0 +1,72 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020-present Cloudogu GmbH and Contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+import React, { FC } from "react";
+import Icon from "../Icon";
+
+type Props = {
+  onChange?: (value: boolean) => void;
+  checked: boolean;
+  indeterminate?: boolean;
+  disabled?: boolean;
+  label?: string;
+};
+
+const TriStateCheckbox: FC<Props> = ({ onChange, checked, indeterminate, disabled, label }) => {
+  const onCheckboxChange = () => {
+    if (onChange) {
+      console.log("clickediclick");
+      onChange(!checked);
+    }
+  };
+
+  let icon;
+  if (indeterminate) {
+    icon = "minus-square";
+  } else if (checked) {
+    icon = "check-square";
+  } else {
+    icon = "square";
+  }
+
+  let className;
+  if (!checked || indeterminate) {
+    className = "far";
+  } else {
+    className = "fa";
+  }
+
+  let color;
+  if (disabled) {
+    color = "grey-light";
+  } else if (checked || indeterminate) {
+    color = "blue";
+  } else {
+    color = "black";
+  }
+
+  return <><Icon iconStyle={"is-outlined"} name={icon} className={className} color={color} />{" "}
+  {label}</>;
+};
+
+export default TriStateCheckbox;