[qtcontacts-sqlite] Treat "other" display label group specially. Contributes to JB#46650

See merge request !34

Ensure that the ordering for the "other" group (?) is treated
specially, similarly to the order for the "numbers" group (#).

tests: skip tst_displaylabelgroups() if MLITE is not available

See merge request mer-core/qtcontacts-sqlite!33

This is a workaround for issue #5.

We also remove the `CONFIG += link_pkgconfig` from `engine.pro` because
this directive is already set in `config.pri`.

Tests, QContactManager: wipe contacts after each test

See merge request !25

This contact is not normally returned by the QContactManager::contacts()
method, so it's not being delated by our newly added cleanup() method.

[qtcontacts-sqlite] Allow overriding plugin directory

See merge request !29

This is needed in order to run the tests directly from the build dir.

[qtcontacts-sqlite] Access columns via a mutable index

See merge request !28

[qtcontacts-sqlite] Add missing includes

See merge request !32

Tests, DisplayLabelGroups: remove contacts-private dependency

See merge request !27

This makes it easier to move fields around without having to change a
lot of code; this is especially useful when trying to reduce git diffs
(and conflicts).

[qtcontacts-sqlite] Properly emit changes to display label groups. Contributes to JB#45836

See merge request !31

Previously we emitted asynchronously before the transaction was
committed.  This commit ensures that we emit only if the transaction
is committed successfully by the writer thread, ensuring that there
is no race between readers attempting to access the updated
display label groups list, and the completion of the write.

Tests: don't depend on QtGui

See merge request !24

[qtcontacts-sqlite] Add `override` to virtual methods

See merge request !23

[contacts] Fix default sort order. Fixes JB#45731

See merge request !22

Configuration default should be First Name, not Last Name.

Tests: launch a temporary D-Bus session

See merge request mer-core/qtcontacts-sqlite!21

build: Fail build on undefined symbols

See merge request mer-core/qtcontacts-sqlite!20

Add .gitignore

See merge request mer-core/qtcontacts-sqlite!19

[qtcontacts-sqlite] Improve DLG plugin interface. Contributes to JB#44742

See merge request mer-core/qtcontacts-sqlite!17

[qtcontacts-sqlite] Allow empty sub-type for urls and anniversaries. Contributes to JB#44713

See merge request !18

Make it possible to specify a url/anniversary without a sub-type.

This commit improves the display label group plugin interface by
allowing plugins to report whether the specified locale is a
preferred locale for them, rather than merely valid, as some
plugins may work in multiple locales but should be preferentially
used (e.g. to determine the default display label groups) for
a subset of those locales.

For example, a pinyin grouping plugin might be valid in all locales
but preferred in locales which use Simplified Han writing script.

The database now populates the "default" supported display label
groups from the highest priority preferred plugin rather than
the highest priority valid plugin (falling back to highest priority
valid plugin if no preferred plugins exist for the current locale).

[qtcontacts-sqlite] Cleanups. Contributes to JB#38781

See merge request !16

Fix style, remove dead code etc.

And fix build in CI