Allow enabling developer mode from local package.

See merge request !126

[developermode] Implement installing from local package. Contributes to JB#47559

This allows enabling developer mode from local package and thus doesn't
require Internet or repository access. The package must not have
non-preinstalled requirements. Before installing version in package file
name is checked against -preload subpackage.

[developermode] Add repositoryAccessRequired property. Contributes to JB#47056

Repository access may be required if the local package does not exist or
it can not be installed for some reason. In that case developer mode
settings page must ask for repository access (usually some kind of
account).

[systemsettings] Update plugins.qmltypes. Contributes to JB#48047

See merge request !127

[LocationSettings] Allow Yandex Locator services. Fixes JB#47250

See merge request !111

[aboutsettings] Add property with localized version. Contributes to JB#47664

See merge request !124

[nemo-systemsettings] Cleanup hardcoded nemo user. Fixes JB#47605

See merge request !123

[nemo-systemsettings] Make AboutSettings easily stubbable. Contributes to JB#47601

See merge request !122

Update VpnModel to use libconnman-qt VPN API

See merge request !113

To allow the base class in libconnman-qt to be more easily named as
VpnModel. The class has been renamed in libconnma-qt to align with the overall
libconnman-qt class naming approach.

Functionality from VpnModel has now been moved into libconnman-qt
VpnCoreModel. This updates VpnModel to use this libconnman-qt VPN API,
by extending VpnCoreModel, rather than interacting with connman directly
through its dbus interface.

[nemo-systemsettings] Expose symlink from UDisks2 block. Contributes to JB#47352

See merge request !121

[nemo-storage] Expose private UDisks2 block. Contributes to JB#47352

See merge request !120

This is not a public class. Thus, there is no guarantees what so ever
that the API remains there like this.

Allow certificate model to decode in-memory PEMs

See merge request !116

The certificate model code allows an X509 certificate (or bundle of
certificates) to be loaded from disk so they can be used to the UI
(e.g. for displaying certificate details).

This change allows PEM data to be provided as a QByteArray, rather than
as a file, allowing certificates store in memory to be accessed by the
UI as well, without having to generate a temprory file.

This change also exposes certificate summary info, providing some
addition properties that help when displaying a summary of the
certificate.

[aboutsettings] Add property with localized OS name. Contributes to JB#47268

See merge request !118

Localization is loaded from /etc/os-release-l10n, which has ini syntax:

    [en-US]
    NAME = Value

If there is no localization, value from /etc/os-release used as fallback.

[plugin] Register Partition metatype. Contributes to JB#46822

See merge request !119

[nemo-systemsettings] Add deprecation warning. Contributes to JB#46991

See merge request !117

[settings-storage] Expose externalStoragesPopulated property. Contributes to JB#46110

See merge request !115

[nemo-storage] Do not accept invalid block devices. Fixes JB#46420

See merge request !110

A block device that is dm device must have crypto backing device.

Clear partition wait timers when a block is removed. Also destroy block
explicitly when block is removed. Previously we started another wait
timer when block completed (after all interfaces were checked).

[systemsettings] Update plugins.qmltypes. Contributes to JB#46477

See merge request !109

QtQuick 2.0 is now correctly listed as a dependency and the standard
components are omitted thanks to making qmlimportscanner available at
the time qmlplugindump is executed.

[systemsettings] Expose baseOperatingSystemName that does not contain OS suffix.  Contributes to JB#46079

See merge request !108

[systemsettings] Expose baseOperatingSystemName that does not contain OS suffix. Contributes to JB#46079

Support VPN ordering by connected status

See merge request !106

This change adds the `orderByConnected` flag to VpnModel which, when
set, will order VPN connections in the model first by the connection
status (connected first, followed by not connected), then by the name
alphabetially ascending (case-sensitive).

When not set, the previous case-sensitive alphabetic name ordering is
used.

The new ordering is used when the MDM policy is set to prevent the user
from manually connecting or disconnecting the VPNs. In this case, the
list of VPNs is presented differently with headers indicating connection
status, rather than indicating it using a TextSwitch glassitem.

Do not expose /home and / partitions through udisk block devices

See merge request !107