Create geos-pv package and add PVGeosLogReader plugin

[mlemayTTE]

The objective of the PR is to create geos-pv package that will gather all the Paraview plugins that wrap vtk filters.

More precisely, the work to do in this PR is to:

• create and set the package up
• move the file PVGeosLogReader from geos-posp/src/PVplugins to geos-pv

geos-pv package will not be included in the build ci because it would requires paraview dependency. The build of geos-pv package together with Paraview will be tested later.

However, Paraview plugins must be loadable in any Paraview. It requires to add all dependent geos python package paths. A first fix was done in the PR #67 but needs to be consolidated.

The other Paraview plugins from geos-posp will be moved later together with testing associated vtk filters and doc.