Consider: handle docker entrypoints in VM runtime

[nieznanysprawiciel]

Why:

• developers wants entrypoint support

What:

• check why it was not supported initially (ask @prekucki or consider old notes)
• estimate effort needed to add the support

[mfranciszkiewicz]

Entrypoints were not supported at first due to a narrowed down feature scope of initial releases. Entrypoint handling is implemented in the init process, although entrypoints are never executed and the code was not tested.

We need to extend runtime's capability list in order to make providers / runtimes with entrypoint support discoverable on the market, while remaining backward-compatible.

Estimation:

• 2 workdays (incl. testing)