... after logging in via Tails Greeter. Now we do some very important
stuff there, like enabling the accessibility toolkit in GNOME. That is
specifically something we lose if we forgot to run that step after
rebooting, which specifically was a problem in at least one scenario
(Deleting a Tails persistent partition).

While we're at it, let's also run the 'Tails Greeter has dealt with
the sudo password' step at the same time.

Dogtail's stdout can contain other stuff, like debug logging, so let's
match the type of lines we are looking for.

The new version decreases the size of the seed text box (the old image
expects a larger one), and it is not focused by default. Furthermore,
there seems to be a race between the where Sikuli could detect the old
text box after clicking next, so let's properly wait for the
verification window.

refs: #11199

Closes: #11202

With this step implemented with Dogtail, we don't refer to camel cased
.png:s any more, but to the actual label, e.g. "Some application"
rather than "SomeApplication".

The ScriptProxy part was a remnant from the time when I was still
concidering supporting Dogtail's procedural API, but it's now clear
that it will be too hard and not offer anything beyond the Tree
API. Also, the `interact` + block idea was from this time, and also
from a part of rewritten Git history where each use of the Dogtail
class instance inside the? `interact` block built up a single script,
that then was executed. However, since you can mix-in other calls
(e.g. to Sikuli) that may expect that a change already has happened,
that seemed like a bad approach.

So, let's KISS and simply settle on the classes Application and Node,
roughly reflecting those classes in the Tree API. The diff might look
scary, but it just moves code around, and removes some confusing
parts.

This partially reverts commit 9d82539e.

The reason is that Dogtail (or rather the a11y/AT-SPI stack it builds
on) has issues with pinentry. E.g. accerciser simply cannot see it,
and everything else experiences a long delay => the tests take much
longer to run.

I've seen instances where `config.searchShowingOnly` is set multiple
times, which makes sense -- we add it for each component.

This will greatly speed up VM.file_{append,overwrite}() and in
particular make it much faster to transfer Dogtail scripts.

If this idea turns out working well, this should be upstreamed.

Epic simplification++

Refs: #10721

This provides a simple interface for generating python code, sending
it to the guest, and executing it.

Refs: #10721

Test suite: fix step that runs commands in GNOME Terminal, that was broken on Jessie when a Terminal is running already.

Will-fix: #11176