Remove use of Mesh.qml to define QgsMeshLayer style

We should avoid using a .qml file to define QgsMeshLayer style:

• invalid min/max values are displayed for dataset
• we lose all previously defined style for dataset

Instead we should use style from input layer if available. In case of mesh creation we should only define mesh display configuration:

• native mesh display
• define line color
• define line size

See commit c2ef2e5f for current implementation for CLC projection.