sync cmd: Rework view/ui layer to show actions that are performed

[andygrunwald]

Context

This PR is a bit bigger (code line-wise).
It is reworking the UI to

• make it a bit simpler to understand (e.g., via fewer message types)
• list the operations in the UI

Caveats

sendMetrics

Right now, the sendMetrics command is shown with a spinner. When completed, it disappears and is not shown in the list of performed operations.
This part needs rework anyway to remove it from the logic where we are running a browser.
This will be done in a future pull request.

TODOs

A few things are still open - Those may be done in future pull requests (to avoid this is getting bigger)

• Rework sendMetrics command logic --> Fixed in sync cmd: Move sendMetrics out of the event loop #107
• Show progress bar only when we are ready to launch a browser (the client can fail before we even think about starting a browser)
• When an error appears, but the program can continue, list the error in the same way as a normal operation --> Fixed in sync cmd: Display errors that don't abort the program as normal UI actions #106

[brgmn]

This is dope! ;) Much better user experience! Thanks!