Fleet: Add created-by to workload resources

[manno]

Internal ref: SURE-7092

Users are unable to tell who created which GitRepo and when looking at deployed workloads, it's equally unclear whom they belong to.

Idea:

• UI adds user/displayname label to created GitRepos
• Fleet copies those labels onto bundles, etc. (this already works)
• UI can show the created-by name in resource views

Label names to use, https://fleet.rancher.io/ref-configuration#labels :

fleet.cattle.io/created-by-user-id
fleet.cattle.io/created-by-display-name