Container Support

Return an empty string when the key does not exist

In this commit, there was also fixed the output format of the field Cmd.

In the past, we had been returning: "container_config":{"Cmd":"/bin/sh -c #(nop) ADD file:ab8940a9b8a62d2f2c4634bf5e63a87ea73736bd0313412e41be2351c4fbdf53 in / "}.

As of now, the command is wrapped by a list: "container_config":{"Cmd":["/bin/sh -c #(nop) ADD file:ab8940a9b8a62d2f2c4634bf5e63a87ea73736bd0313412e41be2351c4fbdf53 in / "]}

closes #8348 https://pulp.plan.io/issues/8348

backports #8299 https://pulp.plan.io/issues/8299

(cherry picked from commit c9bca5911004145c8406f373232a536858888bb4)

Return an empty string when the key does not exist

In this commit, there was also fixed the output format of the field Cmd.

In the past, we had been returning: "container_config":{"Cmd":"/bin/sh -c #(nop) ADD file:ab8940a9b8a62d2f2c4634bf5e63a87ea73736bd0313412e41be2351c4fbdf53 in / "}.

As of now, the command is wrapped by a list: "container_config":{"Cmd":["/bin/sh -c #(nop) ADD file:ab8940a9b8a62d2f2c4634bf5e63a87ea73736bd0313412e41be2351c4fbdf53 in / "]}

closes #8348 https://pulp.plan.io/issues/8348

backports #8299 https://pulp.plan.io/issues/8299

(cherry picked from commit c9bca5911004145c8406f373232a536858888bb4)