Allows to upload a key to providers that use a different api uri than
api.provider.net

- Resolves: #8868

When setting the listeners in the IMAP Folder, we avoid setting more
than one listener for the same imap mailbox (because in some situations
we were registering way too many listeners).

this was making the pixelated inbox registering the notification and
therefore the imap mailbox not being registered.

this MR also refactors the way pixelated is initialized, so that it
avoid creating a second Account instance. In this way, we make sure that
the pixelated mua and the imap server share the same collections for a
given mailbox, and therefore any of the two is able to get a
notification whenever the other adds a message to the mailbox.

- Resolves: #8846, #8798

- Resolves: #8886

This fixes two bugs with handling the autoconf parameter:
 - It looks for "True" instead of "true" in the dispatching code to
   account for json.dumps() converting true into a boolean and str()
   returning the python-style capitalized version "True".
 - It moves the initial definitions of offirst_bootstrap,
   ongoing_bootstrap, and stuck_bootstrap into the class instantiation
   method so they don't get shared between instances of the
   class. Previously, this caused one instance being bootstrapped to
   causes other instances to think they were also actively being
   bootstrapped.

Resolves #8843

- Resolves: #8873

None is recognized as not-default and gives an error if the
searched config value is not present in the config file. This was
provoking an error with manhole not being configured.