`unittest.TestCase` is deprecated.

…hortname/abstract/etc

Add QGIS Server tab to QgsVectorTileLayerProperties for configuring shortname/abstract/etc

instead of the generic QgsException one
Refs warning in qgis#55481 (comment)

```
/tmp/work/geography/qgis/work/qgis-3.28.13/build/python/core/build/_core/sip_corepart0.cpp:38168: warning: exception of type 'QgsProviderConnectionException' will be caught
38168 |             catch (QgsProviderConnectionException &sipExceptionRef)
      |
/tmp/work/geography/qgis/work/qgis-3.28.13/build/python/core/build/_core/sip_corepart0.cpp:38158: warning:    by earlier handler for 'QgsException'
38158 |             catch (QgsException &sipExceptionRef)
```

This is achieved with the two following changes:
- add QgsDummyLayer to handle technical layer (for example terrain).
- add QgsTerrainLayer3DRenderer to handle terrain layer.

With this change, this is now possible to remove `mSceneEntities` as
the entities are now also saved in mLayerEntities.

…oid confusion with Qgs3DMapScene::SceneState

The update scene logic is duplicated in two different places:
- `Qgs3DMapScene::updateScene`
- `Qgs3DMapScene::onFrameTriggered`

In `Qgs3DMapScene::updateScene`, it iterates through the different
mapscene entities, check if th gpu limit has been reached and updates
the scene state flags accordingly.
In `Qgs3DMapScene::onFrameTriggered`, it makes the same thing as
`Qgs3DMapScene::updateScene` but only if needed.
These similar approaches are merged into one by adding a `forceupdate`
boolean.

…eLog and qInstallMessageHandler)

This produces:

* a cleaner and more understandable log management
* all log logic is in QgsLogger::qtMessageHandler
* log format cutomisation via QT_MESSAGE_PATTERN (useful for dev/server usage)
* log message formating is delegated to Qt
* add QGS_LOG_LVL_XXX to help in understand map between number and level

This routine tries to estimate the GPU available memory in kb. It uses
some vendor OpenGL extensions. It works for AMD and Nvidia but there
is no available extension for an Intel card. It returns -1 in case of
failure.

…grate log from qDebug to QgsDebugMsgLevel

The entity is deleted, not the entry.

This way, it is created and deleted by the same class.

This prevents a memory leak.

…emporary container"

…t used"