[25.0 backport] pkg/system: return even richer xattr errors

[thaJeztah]

• backport pkg/system: return even richer xattr errors #47174
• Follow-up to Fail unpacking images with xattrs to filesystems without xattr support #45464
• Related to Problems adding files to image following 25.0.0 upgrade #47137

The names of extended attributes are not completely freeform. Attributes are namespaced, and the kernel enforces (among other things) that only attributes whose names are prefixed with a valid namespace are permitted. The name of the attribute therefore needs to be known in order to diagnose issues with lsetxattr. Include the name of the extended attribute in the errors returned from the Lsetxattr and Lgetxattr so users and us can more easily troubleshoot xattr-related issues. Include the name in a separate rich-error field to provide code handling the error enough information to determine whether or not the failure can be ignored.

(cherry picked from commit 43bf65c)

- Description for the changelog

- To assist in troubleshooting, the name of the xattr which could not be set is now reported in error messages

- A picture of a cute animal (not mandatory but encouraged)

[thaJeztah]

Failure is unrelated, and tracked in #47119

=== Failed
=== FAIL: amd64.integration.system TestDiskUsage/empty (0.00s)
    disk_usage_test.go:41: assertion failed: 
        --- du
        +++ →
          types.DiskUsage{
        - 	LayersSize: 4096,
        + 	LayersSize: 0,
          	Images:     {},
          	Containers: {},
          	... // 3 identical fields
          }
        
    --- FAIL: TestDiskUsage/empty (0.00s)

=== FAIL: amd64.integration.system TestDiskUsage (2.62s)