Refactor the (container) run command flagging process

### What is the problem you're trying to solve

I'm currently refactoring the process of handling flags for the (container) run command. However, it is very complex and I would like to discuss it further.

### Describe the solution you'd like

First, we should split the `createContainer` function into smaller functions. As seen in the code at https://github.com/containerd/nerdctl/blob/1bbfe6930c56f3d69fe05b300f7c2817b828c024/cmd/nerdctl/container_run.go#L408-753
We will divide it into three tasks:

1. Move all helper functions to `pkg/cmd/*util`;
2. Add a function `processInternalLabels`;
3. Move all flag retrieval to `processCreateContainerFlags`.

Next, we will move `createContainer` to `pkg/cmd/containerutil`.

Finally, we will create `ContainerRunOptions` in `pkg/api/types/container_types.go` and `Run` in `pkg/cmd/container/run.go`.

Due to the complexity of the `createContainer` function and its numerous helper functions, it will take more time to handle.

@AkihiroSuda @djdongjin @Zheaoli , WDYT? Can you share your ideas?

### Additional context

_No response_