[Breaking][CDTOOL-1256] Move domainv1 commands to domain and move prior domain command to service/domain

[rcaril]

Change summary

All Submissions:

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

New Feature Submissions:

• Does your submission pass tests?

make test TEST_ARGS="-run TestDomainCreate ./pkg/commands/domain"
ok      github.com/fastly/cli/pkg/commands/domain       1.063s
make test TEST_ARGS="-run TestDomainList ./pkg/commands/doma
in"
ok      github.com/fastly/cli/pkg/commands/domain       1.044s
make test TEST_ARGS="-run TestDomainDescribe ./pkg/commands/
domain"
ok      github.com/fastly/cli/pkg/commands/domain       1.045s
make test TEST_ARGS="-run TestDomainUpdate ./pkg/commands/do
main"
ok      github.com/fastly/cli/pkg/commands/domain       1.052s
make test TEST_ARGS="-run TestDomainDelete ./pkg/commands/do
main"
ok      github.com/fastly/cli/pkg/commands/domain       1.044s

---
make test TEST_ARGS="-run TestDomainDelete ./pkg/commands/service/domain"
ok      github.com/fastly/cli/pkg/commands/service/domain       1.047s
make test TEST_ARGS="-run TestDomainValidate ./pkg/commands/
service/domain"
ok      github.com/fastly/cli/pkg/commands/service/domain       1.072s
make test TEST_ARGS="-run TestDomainUpdate ./pkg/commands/se
rvice/domain"
ok      github.com/fastly/cli/pkg/commands/service/domain       1.051s
make test TEST_ARGS="-run TestDomainDescribe ./pkg/commands/
service/domain"
ok      github.com/fastly/cli/pkg/commands/service/domain       1.059s
make test TEST_ARGS="-run TestDomainList ./pkg/commands/serv
ice/domain"
ok      github.com/fastly/cli/pkg/commands/service/domain       1.062s
 make test TEST_ARGS="-run TestDomainCreate ./pkg/commands/se
rvice/domain"
ok      github.com/fastly/cli/pkg/commands/service/domain       1.049s

Changes to Core Features:

• Have you written new tests for your core changes, as applicable?
• Have you successfully run tests with your changes locally?

User Impact

Service version oriented domain commands have been moved under the service domain command. Versionless domainv1 commands have been moved to the domain command.

Are there any considerations that need to be addressed for release?

End users that are using the CLI in any workflows for domains will need to update accordingly for these command changes.