Copy files to running container without requiring oc binary

[kadel]

Functions that are copying files to the container (occlient.RsyncPath and occlient.CopyFile) are still calling oc binary.
We should figure out a way how to do it do it without oc binary just with pure client-go.

Let's start with CopyFile copying one file might be fairly easy, as we can check how it is implemented in kubectl cp

When we have that we might not even need RsyncPath. We are already detecting file changes in watch command, so we can just copy modified files one-by-one using CopyFiles (don't forget about deleted files). This will also remove dependency on rsync that is a complication, especially for windows users.

parent: #257