Handle returned errors from mannequin duplicate entry error

## Description

Dependent on fix for: [#7030]( https://github.com/github/octoshift/issues/7030)

Within the [HandleReclaimationResult](https://github.com/github/gh-gei/blob/5dc7c8eba9c582c8e6bfd5a4017f62835e4cecbd/src/Octoshift/Services/ReclaimService.cs#L220) function, we will need to capture and handle the error message returned from GH indicting the reclamation failure and the reason behind it.

## Reproduction Steps
1. Find an issue or PR with multiple mannequins
2. Attempt to reattribute the same claimant to each of the mannequins within the issue/PR (i.e. `/GHES-testing2-repo/issues/7`)
3. Go to import/export and note that attribution invitations are listed as `accepted` without having been `completed`