[BugFix] Explicit params and buffers

[agrotov]

Description

Added params and buffers as explicit arguments to the forward functions.

Motivation and Context

Motivation
For functional evaluation, we pass the module params (and possibly buffers) together with the inputs of the module (stored in a TensorDict) using

def forward(self, tensordict, **kwargs):
params = kwargs.get("params", None)
buffers = kwargs.get("buffers", None)
...
However, this breaks when using higher.

We should have default values for these instead of using get("params", None) etc.

The changes should be compatible with: TensorDictModule, TensorDictSequence and ProbabilisticTensorDict.

close #419

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Types of changes

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• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds core functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (update in the documentation)
• Example (update in the folder of examples)

Checklist

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• I have read the CONTRIBUTION guide (required)
• My change requires a change to the documentation.
• I have updated the tests accordingly (required for a bug fix or a new feature).
• I have updated the documentation accordingly.

[vmoens]

Wonderful! Thanks for this!

[agrotov]

Fixed types!