v1.7.1: Prompt again (#165)

* survey: pass previous invalid value to Prompt

Support different behavior after a validation error in repeated prompts.

Signed-off-by: Mate Ory <mate.ory@banzaicloud.com>

* editor: recall previous invalid input

Recall the previous invalid input in the repeated prompt so the user
doesn't have to start over typing the answer.

Signed-off-by: Mate Ory <mate.ory@banzaicloud.com>

* survey_test: check recalling invalid Editor input

* tests: add prompt-again editor manual test