Memory ownership and lifecycle management between FORM and Phlex

[barnaliy]

Proposed Fixes (Follow up from PR#379)

In form/root_storage/root_tbranch_container.cpp: Add a reset for the branch address to prevent invalid references.

In form/form_source.cpp: Update the logic to either free the memory after the copy or, preferably, transfer the pointer ownership to the Phlex framework. 

Safety Check: Ensure memory is freed even in cases where the data is read but not successfully passed to Phlex.

@aolivier23 , @pcanal , @barnaliy