[dev] feat(moe): Support packed sequence for gated delta net (GDN)

[yuzhongw-nvidia]

What does this PR do ?

Support packed sequence for gated delta net (GDN).

PR for main: #2645

Contribution process

flowchart LR
    A[Pre-checks] --> B[PR Tests]
    subgraph Code Review/Approval
        C1[Expert Review] --> C2[Final Review]
    end
    B --> C1
    C2 --> D[Merge]

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[yuzhongw-nvidia]

/ok to test ae8806c

[yuzhongw-nvidia]

/ok to test 545a2a5

[kunlunl]

Also need to update this line https://github.com/yuzhongw-nvidia/Megatron-LM/blob/befbcd2a10b60deb4edbd0f758275b26a6df83c7/megatron/core/ssm/gated_delta_net.py#L741 to param = param[tuple(slices)]?

[yuzhongw-nvidia]

Also need to update this line https://github.com/yuzhongw-nvidia/Megatron-LM/blob/befbcd2a10b60deb4edbd0f758275b26a6df83c7/megatron/core/ssm/gated_delta_net.py#L741 to param = param[tuple(slices)]?

Thanks. Resolved.

[kunlunl]

/ok to test 80d2d1c