[CDTOOL-1218] Add Support for NGWAF Redaction Commands

[rcaril]

Change summary

This PR adds support for the NGWAF redaction commands.

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 TestRedactionCreate ./pkg/commands/ngwaf/redaction"
ok      github.com/fastly/cli/pkg/commands/ngwaf/redaction      (cached)

 make test TEST_ARGS="-run TestRedactionDelete ./pkg/commands/ngwaf/redaction"
ok      github.com/fastly/cli/pkg/commands/ngwaf/redaction      (cached)

make test TEST_ARGS="-run TestRedactionRetrieve ./pkg/commands/ngwaf/redaction"
ok      github.com/fastly/cli/pkg/commands/ngwaf/redaction      (cached)

make test TEST_ARGS="-run TestRedactionList ./pkg/commands/ngwaf/redaction"
ok      github.com/fastly/cli/pkg/commands/ngwaf/redaction      (cached)

make test TEST_ARGS="-run TestRedactionUpdate ./pkg/commands/ngwaf/redaction"
ok      github.com/fastly/cli/pkg/commands/ngwaf/redaction      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?

[anthony-gomez-fastly]

1 nit, otherwise LGTM