[web] Optimized images on tools.

.../meshing-submeshes/submeshes/02_bulk_mesh_top_surface.png

...eshes/03_bulk_mesh_with_ids_top_surface_bulk_node_ids.png

...s/meshing/addlayer/SimpleQuadExampleWithNewTopLayer_1.png

...ntent/docs/tools/meshing/addlayer/SimpleQuadExample_1.png

...tent/docs/tools/meshing/gmsh-interface/square_1x1.gml.png

...msh-interface/square_1x1_adaptive_point_density_0.005.png

...gmsh-interface/square_1x1_adaptive_point_density_0.05.png

.../gmsh-interface/square_1x1_adaptive_point_density_0.5.png

.../meshing/gmsh-interface/square_1x1_plus_subgeometries.png

...re_1x1_plus_subgeometries_adaptive_point_density_0.05.png

...are_1x1_plus_subgeometries_adaptive_point_density_0.5.png

...nt/docs/tools/meshing/gocadsgridreader/WorkflowGO2OGS.png

...ing/gocadsgridreader/flow_simulation_klein_Grid_Rinne.png

...hing/remove-mesh-elements/ExampleRemoveElements-Input.png

...ing/remove-mesh-elements/ExampleRemoveElements-Output.png

...ed-mesh-generation/structured_grid_hex456_non-uniform.png

...ctured-mesh-generation/structured_grid_hex456_uniform.png

...uctured-mesh-generation/structured_grid_quad34_hex456.png

web/content/docs/tools/meshing/vtu2grid/vtu2grid-100.png

web/content/docs/tools/meshing/vtu2grid/vtu2grid-200.png