Manipulators: add input filter field to apply block and apply filter only block

[edoardolombardi]

The developments add:

• an input to Apply block dedicated to a filter field to modulate the geometry deformation field;
• a new block (ApplyFilter) that applies a scalar filter field to a vector deformation field.

Starting from #152

Compiled with https://github.com/optimad/bitpit/commit/2ae49a8e00da488411ddb36a140505d4761e6d7e

EDITED AFTER MERGE: Compliant with new bitpit tip master commit: https://github.com/optimad/bitpit/commit/53b82749aa03676c3f0912a333ab1fb9454bdaca

Note: the ApplyFilter block can be included in a future generic class (e.g. FieldOperations) as multiplication between scalar and vector fields defined on portions of the same geometry MOVED TO ISSUE -> #156