Make rocksdb configurable (backport #1658)

[mergify]

This is an automatic backport of pull request #1658 done by Mergify.
Cherry-pick of 90fbe1a has failed:

On branch mergify/bp/release/v0.23.x/pr-1658
Your branch is up to date with 'origin/release/v0.23.x'.

You are currently cherry-picking commit 90fbe1aa.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   .github/workflows/ci-rocksdb-build.yml
	modified:   Makefile
	new file:   cmd/kava/opendb/opendb.go
	new file:   cmd/kava/opendb/opendb_rocksdb.go
	new file:   cmd/kava/opendb/opendb_rocksdb_test.go
	modified:   go.mod
	modified:   go.sum

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   Dockerfile-rocksdb
	both modified:   cmd/kava/cmd/root.go

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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