When processing the buttons in the header of the arch,
the listArchParser did not use the method on this.
This was a significant drawback when trying to extend
the behavior of the parser.
After this commit, the processing of the button goes
through the existing method on this, making it possible
to extend that behavior. Note that for the processing
of the other buttons in the arch, this modification has
already been done earlier.
task-3072937
closesodoo/odoo#126400
Signed-off-by: Lucas Perais (lpe) <lpe@odoo.com>