Ability to select nodes in the TIF tree to include in the write / difference operation

[paul-bowden]

If an update to an existing environment has to be deployed, the user must be able to select/deselect objects from the TIF tree.

The use case is, that departmental modifications to the core model could have been made and the core changes are not allowed to take effect to these changes.

Selections which have been made once, shall be stored in the user environment, that a user don't need to rebuild each selection in every deploy process.

Deploying only a subset of a solution / diff would require a proper selected artificats dependencies verification mechanism to be more secure.