Run LDAP and Office365 import asynchronously in the interface

[marien-probesys]

Problem

Following #310, these tasks will be run automatically in background. However, an admin who would trigger the imports from these connectors still could face a timeout if the tasks are too long. Also, the admin could trigger several imports in parallel, which we don't want.

Specifications

Button markup

Change the import button which is an anchor to a real button.

Run the import asynchronously

When clicking on the import button, dispatch a message to import the connector data asynchronously.

Add feedback on running imports

Block the "import" buttons if an import is already running.

• Add a importStartedAt field to the main connector class
• When the import starts, set this field to the current date
• When the import ends, set this field to null
• When the field is set, disable the import button and show a message saying that an import is already running