Add support for WithCreateContainerParametersModifier

[Xitric]

This PR adds a new builder method WithCreateContainerParametersModifier() which corresponds to withCreateContainerCmdModifier() from the Java implementation.

The purpose of this method is to gain access to low-level configuration on the Docker.DotNet client, for instance to configure Ulimits, without having to expose all of these low-level configurations through the testcontainer builder.

Merging this PR closes #481.

[HofmeisterAn]

I won't be able to do the review until the beginning of next week - sorry, but thanks already for your pull request and contribution.

[HofmeisterAn]

Thanks for your contribution. I added some minor suggestions and improvements. Could you please cover your changes with a unit test in: DotNet.Testcontainers.Tests.Unit.Containers.Unix.TestcontainersContainerTest.WithConfiguration. Something like:

...
.WithCreateContainerParametersModifier(parameters = parameters.Name = "Foo")
.WithCreateContainerParametersModifier(parameters = parameters.Name = "Bar")
...

Assert("Bar", ...)

[Xitric]

@HofmeisterAn Yes of course I should add a test. I looked around for a short while but I could not determine the right location for it. It has been added now. I just need clarification on a couple of your comments now

[Xitric]

@HofmeisterAn There you go. Also added some unit tests for BuildConfiguration to clarify expectations of the different method implementations. That way we can catch it if someone breaks contract.

I have never used XUnit before, so pardon me if the class structure is not in line with best practices. Let me know if I should use a combination of the static outer class and sealed inner classes (I have seen that in other tests), and I can refactor it.

[HofmeisterAn]

If you like, you can squash the commits. I'll merge the pull request later that day, tomorrow at the latest.

[Xitric]

@HofmeisterAn There we go - squashed into a single commit. Thank you for the collaboration so far 🚀

[HofmeisterAn]

Closes #481.