Move new glimmer style string to its own home

ui/app/components/chart-primitives/v-annotations.js

@@ -1,6 +1,7 @@
 import Component from '@glimmer/component';
 import { htmlSafe } from '@ember/template';
 import { action } from '@ember/object';
+import styleString from 'nomad-ui/utils/properties/glimmer-style-string';
 
 const iconFor = {
   error: 'cancel-circle-fill',
@@ -12,30 +13,6 @@ const iconClassFor = {
   info: '',
 };
 
-// TODO: This is what styleStringProperty looks like in the pure decorator world
-function styleString(target, name, descriptor) {
-  if (!descriptor.get) throw new Error('styleString only works on getters');
-  const orig = descriptor.get;
-  descriptor.get = function() {
-    const styles = orig.apply(this);
-
-    let str = '';
-
-    if (styles) {
-      str = Object.keys(styles)
-        .reduce(function(arr, key) {
-          const val = styles[key];
-          arr.push(key + ':' + (typeof val === 'number' ? val.toFixed(2) + 'px' : val));
-          return arr;
-        }, [])
-        .join(';');
-    }
-
-    return htmlSafe(str);
-  };
-  return descriptor;
-}
-
 export default class ChartPrimitiveVAnnotations extends Component {
   @styleString
   get chartAnnotationsStyle() {

ui/app/utils/properties/glimmer-style-string.js

@@ -0,0 +1,31 @@
+import { htmlSafe } from '@ember/template';
+
+// A decorator for transforming an object into an html
+// compatible style attribute string.
+//
+// ex. @styleString
+//     get styleStr() {
+//       return { color: '#FF0', 'border-width': '1px' }
+//     }
+export default function styleString(target, name, descriptor) {
+  if (!descriptor.get) throw new Error('styleString only works on getters');
+  const orig = descriptor.get;
+  descriptor.get = function() {
+    const styles = orig.apply(this);
+
+    let str = '';
+
+    if (styles) {
+      str = Object.keys(styles)
+        .reduce(function(arr, key) {
+          const val = styles[key];
+          arr.push(key + ':' + (typeof val === 'number' ? val.toFixed(2) + 'px' : val));
+          return arr;
+        }, [])
+        .join(';');
+    }
+
+    return htmlSafe(str);
+  };
+  return descriptor;
+}