Load wsgi middleware from configuration

From https://discuss.tryton.org/t/sentry-sdk-integration/1925/6
it appears that it will be very useful to allow to configure some middleware to apply on the wsgi application.

assigned to @ced

added trytond type::feature + 1 deleted label

New review270521002 at https://codereview.tryton.org/270521002/#ps288491002

added 1 deleted label and removed 1 deleted label

review270521002 updated at https://codereview.tryton.org/270521002/#ps288661002

New changeset b108dd82df17 by Cédric Krier in branch 'default':
Load WSGI middleware from configuration
https://hg.tryton.org/trytond/rev/b108dd82df17

added 1 deleted label and removed 1 deleted label

closed

New changeset 2afc4b8a21b8 by Cédric Krier in branch 'default':
Load WSGI middleware from configuration
https://hg.tryton.org/tryton-env/rev/2afc4b8a21b8