JetpackLoadingIcon component: no visual indication of loading status

**Issue:**

The `` [component](https://github.com/Automattic/jetpack/blob/74d7093905960d2e3b1d18eb9e3079c41add6d6e/projects/plugins/jetpack/_inc/client/components/jetpack-loading-icon/index.jsx) is used to show a static SVG graphic to indicate loading. While there is an alt text prop for the image, there is no visual indication that this component is loading/processing to a user which can be confusing if things are taking longer than average. The component as consumed by Recommendations:

https://github.com/Automattic/jetpack/blob/74d7093905960d2e3b1d18eb9e3079c41add6d6e/projects/plugins/jetpack/_inc/client/recommendations/index.jsx#L66-L76

**Expected:**

At the least I might expect the ability to pass a prop with some text such as "Loading..." which would be visually displayed. An animated loading image would be great, but it doesn't look like `JetpackLoadingIcon` is consumed widely so that seems overkill.

**Misc.**

Internal, reported via: p8oabR-LV-p2#comment-5840

Start with projects/plugins/jetpack/_inc/client/components/jetpack-loading-icon/index.jsx, then inspect its use in projects/plugins/jetpack/_inc/client/recommendations/index.jsx#L66-L76. Confirm how the loading state is presented and verify that Recommendations visibly communicates loading to users without relying only on alt text.

Written by the indexing model from the issue text.