Fix expression test

make sure the style file with the color ramp can be copied to the settings path
Fix dual view test

* References commit 51e01d6
* And issue #11529
fix PyQgsVectorLayer test
Fix occasional crash on exit because of statis network access manager

see https://bugreports.qt-project.org/browse/QTBUG-25789
fix regex for getting layer name
[layout] Add layout measurement and size classes

These classes are used for storing measurements for a layout
(QgsLayoutMeasurement) and sizes for a layout (QgsLayoutSize).
They support storing a measurement unit alongside a measurement
length/size. A new class QgsLayoutMeasurementConverter handles
conversion between different units, including converting to and
from pixels via a specified DPI property.
[layout] Create a page size registry for layout

Adds a new QgsPageSize class and QgsPageSizeRegistry singleton,
which stores and manages known page sizes
[layout] Add base classes for layout
[layout] Add measurement unit handling to QgsLayout
Start porting page items