Rework the parameters system

[vincentcourtois]

Context

• Parameters are currently tedious to understand and implement as descriptors are only applied on one parameter
• We should have just descriptors, and chose the field we want to apply them to when creating parameters on tools, it would allow the use of the same descriptor for different parameters

Needs

As an administrator. I want to be able to Apply the same descriptor to different parameters at tool creation or edition. So that I can reuse them more and stop having to create the same descriptor several times

[vincentcourtois]

Technical consequences

• The API has to be reworked a bit so that the field targeted is in the parameter, not in the descriptor
• The existing parameters have to be updated to have the same targeted field than their descriptor had
• The descriptor have to be updated to remove the targeted field