dotnet logo SSoT

In the GitLab SVGs project there are two instances of the dotnet logo. This effort is to point to a single file which will make it easier to update in the future and more simple to track in the third-party asset tracker that @smccreesh helps maintain.

The two references to the logo are:

• https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/gitlab/project_template.rb#L52 (illustrations/logos/)
• https://gitlab.com/gitlab-org/gitlab/-/blob/master/app/helpers/ci/pipelines_helper.rb#L50 (illustrations/third-party-logos/ci_cd-template-logos/)

Process

1. Duplicate the dotnet logo into the illustrations/third-party-logos/ directory (this will temporarily add a third instance). Because the logo is used in more than just CD/CD templates it will be placed in this more general location.
2. Update the above references to point to this new path.
3. Remove the logos from the illustrations/logos/ and illustrations/third-party-logos/ci_cd-template-logos/ directories.
4. Update the third-party tracker spreadsheet to reference the new logo location (See https://gitlab.com/gitlab-com/legal-and-compliance/-/issues/607).