This can be produced by errors fetching keys from the server.

- Resolves: #8971

I changed most of the logger statements to use a class attribute, in
this way it's easier to identify which class it's logging them.

in some cases I leave a module-level logger, when we're either using
functions or when the module it's too small.

at the same time I did a general review and cleanup of the logging
statements.

the token is set when we get the srp token in the keymanager service,
but it wasn't been propagated properly to the internal nicknym object
that was refactored recently.

here I make the setter write the same token to both keymanager itself
and the nicknym.

some little additional refactors:

- move gpg initialization to a helper method
  in this way it becomes easier to stub the soledad and keymanager
  components, for testing.

- name nicknym token as publicly visible, since i'm accessing
  it from the keymanager object.

- Resolves: #8651

- some pep8 problems
- some confusion with old and new code after merging
from old keymanager

Port of the original commit:
8f1fe8dd4a54fd2bdda2fc78c339ce9b3d0fc331
by Zara Gebru that introduced updating keys in the background.

This was made in the legacy leapcode/keymanager repo, but was lost in
the merge to the unified bitmask-dev.

Original commit message follows:
--------------------------------

- refresh random key in random time
- add get key by fingerprint
- refactor nicknym methods to own file
- tests

- note this do not include a check for
revoked key, since that need some changes
in gnupg

- Related: #6089