Basic copy_to implementation

[gossi]

Impl for #240

I did some research for the API in rust and node clients:

• Rust
  • 1 Method: with_copy_to
  • Multiple target and source options: https://github.com/testcontainers/testcontainers-rs/blob/73ec33e1de5fc1776fc2310add9fd8f51ebd67ba/testcontainers/src/core/copy.rs#L17
• Node
  • Many methods:
    • withCopyContentToContainer()
    • withCopyDirectoriesToContainer()
    • withCopyFilesToContainer()
    • withCopyArchivesToContainer()
  • Plus respective options for each (under types)

For elixir, I choose the method from rust with_copy_to and then use pattern matching against the cases.

I personally only need one case here and did the impl for the most basic one 🙈.

[gossi]

container_test is reporting issues (socket closed). For once, the introduced copy_to_test is failing.