feat: Add an ability to create a project group

[liza-veis]

What feature?

• [x] Add project_permissions table (columns: id, key, name, created_at, updated_at). Limit the name to 100 chars.
• [x] Add project_groups table (columns: id, key, name, created_at, updated_at). Limit the name to 100 chars.
• [x] Add projects_to_project_groups table (columns: id, project_group_id, project_id, created_at, updated_at).
• [x] Add project_groups_to_project_permissions table (columns: id, project_group_id, project_permission_id, created_at, updated_at).
• [x] Add view_project permission (name: "View Project") through migration.
• [x] Add needed models, and services on the backend.
• [x] Add a controller for project_groups with POST /project-groups route
• [x] The payload for group creation should contain name, project_id, user_ids, and permission_ids. Using this payload you will need to create an item in project_groups, then items in project_groups_to_permissions, and then in projects_to_project_groups.
• [x] The key should be automatically generated in the service by turning the name into snake_case.
• [x] The key should be unique for permissions and user_groups table (restriction on db level and check on the backend as well)
• [x] Add validation for request payload and path parameters
• [x] Add new tables to the db schema in readme

Screenshots

No response

[liza-veis]

Projects table will be added here #57

[VeronikaHordus]

Great job, thank you 💯