Removed IbmDb2 adapter

[michalbundyra]

This storage is not defined in the dependent library so it is not possible to use this adapter. As it is dead code it should be removed.

• Is this related to quality assurance?

[weierophinney]

This repository has been closed and moved to laminas-api-tools/api-tools-oauth2; a new issue has been opened at laminas-api-tools/api-tools-oauth2#3.

[weierophinney]

This repository has been moved to laminas-api-tools/api-tools-oauth2. If you feel that this patch is still relevant, please re-open against that repository, and reference this issue. To re-open, we suggest the following workflow:

• Squash all commits in your branch (git rebase -i origin/{branch})
• Make a note of all changed files (`git diff --name-only origin/{branch}...HEAD
• Run the laminas/laminas-migration tool on the code.
• Clone laminas-api-tools/api-tools-oauth2 to another directory.
• Copy the files from the second bullet point to the clone of laminas-api-tools/api-tools-oauth2.
• In your clone of laminas-api-tools/api-tools-oauth2, commit the files, push to your fork, and open the new PR.
  We will be providing tooling via laminas/laminas-migration soon to help automate the process.