Feature kpoland access levels

[klpoland]

This contains ONLY updates to the sharing mechanism, allowing users to:

• Select different sharing access levels
• Update shared users/groups access (downgrade, upgrade, remove)
• Adds back-end functionality for access control (on another branch to be merged into this one)
• Updated UI to accommodate new access levels

Changes to write privileges on the dataset editing page are on a branch checked out from this one and can be merged into this branch when these are approved (keeping all the changes together would make this a difficult to review PR so I separated them).

[lucaspar]

this file uses self.assertEqual, self.assertTrue, self.assertFalse, and self.assertIn from unittest classes; I think we should stick to simple assert statements for consistency. This also has a little syntax highlighting bonus for using a reserved word in Python.

[klpoland]

yeah, noticed this when refactoring, I'll fix that here. haven't run the pre-commit hooks on this branch yet.

[Copilot]

Pull Request Overview

This PR implements a comprehensive access level system for sharing datasets and captures with different permission levels. Users can now assign "Viewer," "Contributor," or "Co-Owner" permissions to shared users and groups, providing granular control over what actions shared users can perform.

• Added three permission levels (Viewer, Contributor, Co-Owner) with specific capabilities for each
• Updated sharing UI with permission level selection and management functionality
• Refactored backend sharing logic to handle permission updates and changes
• Added extensive test coverage for permission checking and updates

Reviewed Changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
gateway/sds_gateway/users/views.py	Refactored ShareItemView to handle unified sharing operations including permission changes and removals
gateway/sds_gateway/users/utils.py	Updated group sharing utility to support permission levels
gateway/sds_gateway/templates/users/partials/share_modal.html	Enhanced UI with permission level dropdowns and Google Drive-style access controls
gateway/sds_gateway/static/js/userSearchComponent.js	Added permission level handling to user search and chip rendering
gateway/sds_gateway/static/js/permission-levels.js	New JavaScript module for permission level management and UI interactions
gateway/sds_gateway/static/css/permission-levels.css	Comprehensive styling for permission level components and visual feedback
gateway/sds_gateway/api_methods/models.py	Extended UserSharePermission model with permission checking methods and dataset author management

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