Bug: DockerImage path arg is misleading

**Describe the bug**



`testcontainers.core.image.DockerImage` has a constructor arg `path` with the following docs:



> path – Path to the Dockerfile to build the image



But actually this doesn't seem to be true. It's rather the context, the path to the directory to build in and the dockerfile itself must be named `Dockerfile`. Especially for testing this is very unhandy. I often have several dockerfiles in the same directory. I'd expect bein able to pass a `context` and the _actual_ `path` to the dockerfile, like



```python

with DockerImage(dockerfile="./caseA.Dockerfile", context=".", tag="casea:latest") as image:

     pass

```



**To Reproduce**



* have a `test.Dockerfile`

* `with DockerImage(path="./test.Dockerfile", tag="test") as image: ...`

* see not too helpful error message from docker itself bubble up



**Runtime environment**



not relevant



---

P.S.: build-args would also be handy

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