Code of flask-dropzone duplicated in the code

[c8y3]

It seems that the code in namespace app.flask_dropzone is copy pasted from the python package Flask Dropzone (https://flask-dropzone.readthedocs.io/en/latest/) in version 1.5.4.
It would be better for maintenance (such as the application of security updates) to handle this dependence as any other, by adding it in the requirements.txt file.
It seems however, that there is a slight difference between the Flask Dropzone code and the one copied in DFIR-IRIS: when instantiating the Blueprint, parameters static_folder and static_url_path are not set:

iris-web/source/app/flask_dropzone/__init__.py

Line 385 in b3a36cd

blueprint = Blueprint('dropzone', __name__)

vs. https://github.com/helloflask/flask-dropzone/blob/1.5.4/flask_dropzone/__init__.py#L380.