import-secrets does not support json secrets with stringData key definitions

[Alberto Bellotti]

I tried importing secrets with the "stringData" definition for values, but they were ignored. Only secrets with the "data" section were honored.

I think the logic here https://github.com/RedHatInsights/bonfire/pull/89/files#diff-98f3050c7cb8942de6a71922230ff5a5cb2baa61c0309f51485a2c7751a7e74bR53 only checks for data before deciding on whether or not to import.