[WIP]6838 support generative and hovernet with TensorRT

[binliunls]

Fixes #6838 .

Description

Add TensorRT support for generative unet and hovernet.

1. For generative unet, the block is that the trt_export API only supports one input shape and corresponding batch range. Therefore this PR aims to extend the API to support multi-input.
2. For the hovernet, the block is mainly the dict type output. To fix this issue, this PR will try to add another list type output for the hovernet, which can be controlled by an input parameter.

Types of changes

• Non-breaking change (fix or new feature that would not break existing functionality).
• Breaking change (fix or new feature that would cause existing functionality to change).
• New tests added to cover the changes.
• Integration tests passed locally by running ./runtests.sh -f -u --net --coverage.
• Quick tests passed locally by running ./runtests.sh --quick --unittests --disttests.
• In-line docstrings updated.
• Documentation updated, tested make html command in the docs/ folder.