Adjust Downloads toast checkmark to be on the left side of the filename label

:page_facing_up: Description

Improve the DownloadToast on both orientations, correcting the checkmark icon that is currently displayed on top of the filename. The label should be on the left side of the filename label.

The final result should be the following:

| V -- filename | | ---- Button |

The checkmark icon has to be aligned with the filename baseline and the button with the filename leading, make sure to apply also padding between filename and button.

Please attach the screenshot for both orientation and also with dynamic font size, to check behavior with accessibility.

The toast in landscape hovers the safe area, this should be refactored to be within the safe area.

Make sure if needed to check orientation in the implementation to check against the size class and not the device type. (horizontalSizeClass)

Here is a link to the PR with image contexts https://github.com/mozilla-mobile/firefox-ios/pull/24773#issuecomment-2659428423

:information_source: Reference Person

FilippoZazzeroni

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