fix: Use LimaUser method instead of host user name

[w-haibara]

Issue #, if available: #399

Description of changes: In nerdctl_config_applier.go, editing .bashrc uses a file path based on the host's username. However, if the host's username contains . or @, lima uses lima as the username instead of the host's username. (ref: https://github.com/lima-vm/lima/blob/a8c703bf8b66d213d00542ef68271cd7b73612ef/pkg/osutil/user.go#L114-L119) Therefore, if the host's user name contains . or @, editing .bashrc fails. This PR fixes this so that you can get the actual username from LimaWrapper.LimaUser().

Testing done: yes

• [x] I've reviewed the guidance in CONTRIBUTING.md

License Acceptance

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[w-haibara]

@vsiravar Thanks for review! I added a test in nerdctl_config_applier_test.go when local user is not a valid linux username.

I have also made additional changes. I would appreciate it if you would review again.

[w-haibara]

Thank you for merge it!