Add a spinner/progress bar to indicate something is happening when compressing a profile

In normal uses the label "Compressing..." on the profile upload panel is shown for a fairly short amount of time (one or two seconds).

However, is some valid scenario it's certainly not the case, it's dozens of seconds. In my case, I was asking someone in the field to do a `*` profile (all registered threads) because the other regular options didn't show anything of interest, and we were hoping to catch something on another thread.

In addition, the duration of this step is variable, depending on the load and speed of the device, so we can't make assumptions.

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-387)