Decrease memory usage of updater

This release decreases memory usage of updater during update process
about 40%. Memory usage is still not ideal but this improves stuff a
lot. There is disadvantage to this change as it increases storage
requirements during update from at maximum twice size of all packages
(installed version and not yet installed one) to thee times (+download
packed files).

* pkgupdate now downloads packages to /usr/share/updater/download
  instead of ram.
* pkgupdate now downloads packages only when plan is approved, not
  before.
* Added memory usage test bench

Fix invalid data type in svupdater autorun

Fix previous fix release

Fix previous fix

Fix localrepo usage detection

Fix localrepo usage detection

Fix invalid UCI value for autorun

Sanitize scripts output and warn about opkg upgrade

Fix problems with boolean values in UCI config

Fix boolean options UCI handling

Fix invalid import in svupdater

Fix errors in supervisor

Fix problems with supervisor

* Fixed multiple bugs in supervisor and few improvements added
* In root config when accessing uci root_dir is now used

Fix updater-supervisor undefined config module

Fix updater-supervisor undefined config

Change API for approvals to be consistent

Change new API for approvals to be consistent

Turris OS 4.x support

* Added support for Turris OS 4.x configuration changes
* opkg-trans was renamed to pkgtransaction
* Morphed syntax in configuration files was dropped
* Package content option was dropped
* Removed some old obsolete migration scripts

Bacport changes introduced for Turris OS 4.x

Backports:
* added new autorun configuration API
* userlists were renamed to pkglists

New subprocess implementation and multiple fixes

Changes:
* Running processes now uses new implementation that is more resilient
  against stucked programs and reports output as soon as it happens
* opkg-wrapper: added possibility to ignore custom feeds
* pkgupdate: consider set root directory when looking for default entry
  config
* Add additional reported states to pkgupdate

Cleanups:
* dropped base.lua as it is part of distribution not updater it self now

Fixes:
* Fix l10n and list settings error when there is no relevant section in
  uci config
* Fix root directory to be used as absolute path because otherwise use
  of this variable broke with changed directory
* opkg-wrapper, localrepo: take in consideration root directory
* Fixed some warning that were failing tests