Background: on Outlook servers and possibly on other providers as well, connect can fail with a UserError.
Before this fix this results in the form view not being able to open because the compute cannot complete.
This fixes that, so that the connection error may be resolved by the user.
Match algorithms other then 'odoo_standard' were not correctly dealt with in the migrated code. For
these algorithms we restore the handling (but with improvements) that was present in the 10.0 version.
Now it is impossible to confirm a connection to a imap server if there is a problem
in one folder. This commit provides a new state field on the folder and e separate
comfirm button per folder.