[Subsidies] Allow creation of "orphaned" SubsidyAttachments

In the current subsidies workflow it is only possible to add attachments after a Subsidy object has been created. In order to make the workflow faster for mass addition of receipts and proofs of payment, it would be beneficial to allow asyncronous addition of SubsidyAttachments prior to linking them to their Subsidy.

Changes required:

• the subsidy FK field should be blank=True, null=True so that they can be created without any relation
• the destination folder path given by subsidy_attachment_path needs to work without a subsidy_id
• the get_absolute_url will also need to be adapted for the same reason
• perhaps the best thing is to have a temporary location for Subsidy-less SubsidyAttachment; when a SubsidyAttachment is then linked to a Subsidy, the location can be moved to the location as it is currently defined
• the SubsidyAttachment should have an extra URL field meant to contain the URL on git.scipost.org where the item is saved to

added impacthigh priorityhigh labels

changed iteration to Two-week Sprint Mar 10, 2024 - Mar 23, 2024

assigned to @gkatsikas

added to epic &4

added typefeature ⭐️ workflowin-progress labels

marked the checklist item the subsidy FK field should be blank=True, null=True so that they can be created without any relation as completed

marked the checklist item the destination folder path given by subsidy_attachment_path needs to work without a subsidy_id as completed

marked the checklist item the get_absolute_url will also need to be adapted for the same reason as completed

marked the checklist item the SubsidyAttachment should have an extra URL field meant to contain the URL on git.scipost.org where the item is saved to as completed

marked the checklist item perhaps the best thing is to have a temporary location for Subsidy-less SubsidyAttachment; when a SubsidyAttachment is then linked to a Subsidy, the location can be moved to the location as it is currently defined as completed

closed with commit e61342d8

mentioned in commit 0fd17d86

mentioned in commit e61342d8