Caching build of Docker actions

Describe the enhancement

In my opinion, in the case of Docker actions, in many cases it is worthwhile to provide the cache for actions build. At least for published in the marketplace, it is possible to pre-build them by GitHub Actions and store as cache.

Currently, Docker actions are built multiple times as the first step of all builds, which is extremely inefficient for complex Docker actions.

Code Snippet
This is due to the way the GitHub Actions worker works.

Additional information

The issue actions/toolkit#47 has been closed indicating a reference to @actions/cache, which however is limited to user data cache only. In this case, we do not have user data, but public actions, and the process is not controlled by the user at this stage (yet).