[v23.3.x] rpk: enable using public API in rpk transform

[vbotbuildovich]

Backport #17023 to branch v23.3.x. Note that this issue was created as a placeholder, since the original PR's commit(s) could not be automatically cherry-picked.
Here are the commands to execute:

git checkout v23.3.x
git checkout -b vbotbuildovich/backport-17023-v23.3.x-594
git cherry-pick -x 8618322a8e808c1a47c6d8e2ed685b1119c1c755 cf262d66d57b2359e1fee98270b162959e52f33c b9460c6994b35081aaac3012c9ff0ea3944c2d14 9eaf643fd3b0a5941a120f9c7b059a262a7c562a 61ee37d51bfe7a4891ce7a1ed5e9507a5268b092 ca7046f75bf3c92930c87511e4bafb7fd9f6d3c0 b94a068cf697a147f050e8d4b281ece044cbb3f1 f12a3ab281dcede690bd61c8a6186f6f945ffdee d60737e081e11da4cc63cf1ee857c671b6352d9c 5ba20b62a54eb34cf9344e9d9d3bb447adf377fc c21cdece2a5e1be4f83d66954c39f94b5d6a0c31 6c1c11cdb182f2a02a9cf72034afe65fee6a1d4b

git push origin vbotbuildovich/backport-17023-v23.3.x-594
gh pr create \
  --title "[v23.3.x] rpk: enable using public API in rpk transform" \
  --base "v23.3.x" \
  --label "kind/backport" \
  --head "vbotbuildovich/backport-17023-v23.3.x-594" \
  --draft \
  --repo "redpanda-data/redpanda" \
  --milestone "v23.3.x-next" \
  --body "Backport of PR https://github.com/redpanda-data/redpanda/pull/17023 "

[piyushredpanda]

Merged.