Currently, when the profiler's state changes, the tooltip's text is hardcoded:
See https://searchfox.org/mozilla-central/rev/a82dd14b6bc3d05a6a3facc126607e6d34cc2f53/devtools/client/performance-new/popup/menu-button.jsm.js#268-291

We need to localize this.

The button's label and tooltip are currently handled the old way in a properties file, and we should easily move that to a ftl file instead.

Here is an example:
https://hg.mozilla.org/mozilla-central/rev/33d959e23d7e65bd9f5ca462777d3bbc465ef266

Basically we need to move from "tooltiptext" to "l10nId" when defining the popup, and replace the existing translations in https://searchfox.org/mozilla-central/rev/a82dd14b6bc3d05a6a3facc126607e6d34cc2f53/browser/locales/en-US/chrome/browser/customizableui/customizableWidgets.properties#17-18 by new ones in a FTL file (possibly browser.ftl).

Then we can use these translations on the button with l10n.setAttributes.

try: https://treeherder.mozilla.org/jobs?repo=try&revision=96ee1b7836c5d82bab2fcfc9f77d86d9ef06e42d
try with fixes for failures from previous try: https://treeherder.mozilla.org/jobs?repo=try&revision=792288d268a3460221426125e5d4f449b754d9b7

The profiler popup widget was using the old properties-based way of
translating its label and tooltips. Moreover the tooltips weren't
translated anymore when recording/capturing. This patch fixes this by
moving to Fluent and using Fluent to change the button's tooltips when
the state changes.

This fixes a warning when Fluent translates these buttons: previously it
was removing the content, which we don't control. The proper way is
assigning attributes instead.

This also required touching the style a bit.

Depends on D127677

Depends on D127678

https://hg.mozilla.org/mozilla-central/rev/4aa923342154
https://hg.mozilla.org/mozilla-central/rev/01343fa8b6c5
https://hg.mozilla.org/mozilla-central/rev/86b88ba429a3