Make huaweicloud_compute_instance_v2 importable

[joec4i]

I've ported the importer implementation for huaweicloud_compute_instance_v2 from OpenStack, with a couple minor tweaks for unhandled errors.

This was tested with terraform import without issues:

$ terraform import 'module.test.huaweicloud_compute_instance_v2.instance[0]' xxxxxxxx-xxxxxx-xxxx-xxx-xxxxxx
module.test.huaweicloud_compute_instance_v2.instance[0]: Importing from ID " xxxxxxxx-xxxxxx-xxxx-xxx-xxxxxx"...
module.test.huaweicloud_compute_instance_v2.instance[0]: Import prepared!
  Prepared huaweicloud_compute_instance_v2 for import
module.test.huaweicloud_compute_instance_v2.instance[0]: Refreshing state... [id= xxxxxxxx-xxxxxx-xxxx-xxx-xxxxxx]

Import successful!

The resources that were imported are shown above. These resources are now in
your Terraform state and will henceforth be managed by Terraform.module.test

Note that I haven't run the acceptance tests because I don't have an account suitable for this. Please run the tests for me if you find this PR acceptable.

Cheers!

[niuzhenguo]

Thanks for the patch!
Please help to update the doc as well :)

[joec4i]

Thanks for the patch!
Please help to update the doc as well :)

Thanks @niuzhenguo . I have updated the docs. Please have another look.