[v24.3.x] kafka/debug: add a debug end point for offset_for_leader_epoch

[vbotbuildovich]

Backport #26195 to branch v24.3.x. This issue was created as a placeholder because the original PR's commit(s) could not be automatically cherry-picked.
Here are the commands to execute:

git checkout v24.3.x
git checkout -b manual-backport-26195-v24.3.x-664
git cherry-pick -x f3d4ab10dd 047ef7219a 3e626c8c57 26f86d9bbd

git push origin manual-backport-26195-v24.3.x-664
gh pr create \
  --title "[v24.3.x] kafka/debug: add a debug end point for offset_for_leader_epoch" \
  --base "v24.3.x" \
  --label "kind/backport" \
  --head "manual-backport-26195-v24.3.x-664" \
  --draft \
  --repo "redpanda-data/redpanda" \
  --milestone "v24.3.x-next" \
  --body "Backport of PR https://github.com/redpanda-data/redpanda/pull/26195 "

JIRA Link: [CORE-10221](https://redpandadata.atlassian.net/browse/CORE-10221)

[CORE-10221]: https://redpandadata.atlassian.net/browse/CORE-10221?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ