'Copy to Clipboard' functionality (#163)

* Adds 'Copy to Clipboard' functionality to all code blocks in readOnly

* Show on hover, move to SC

* 💚

* PR feedback

frontend/components/CopyToClipboard/CopyToClipboard.js

@@ -0,0 +1,36 @@
+// @flow
+import React, { PureComponent } from 'react';
+import copy from 'copy-to-clipboard';
+
+class CopyToClipboard extends PureComponent {
+  props: {
+    text: string,
+    children?: React.Element<any>,
+    onClick?: () => void,
+    onCopy: (string, boolean) => void,
+  };
+
+  onClick = (ev: SyntheticEvent) => {
+    const { text, onCopy, children } = this.props;
+    const elem = React.Children.only(children);
+    const result = copy(text, {
+      debug: __DEV__,
+    });
+
+    if (onCopy) {
+      onCopy(text, result);
+    }
+
+    if (elem && elem.props && typeof elem.props.onClick === 'function') {
+      elem.props.onClick(ev);
+    }
+  };
+
+  render() {
+    const { text: _text, onCopy: _onCopy, children, ...rest } = this.props;
+    const elem = React.Children.only(children);
+    return React.cloneElement(elem, { ...rest, onClick: this.onClick });
+  }
+}
+
+export default CopyToClipboard;