dryrun stats observable

[jloftin-nv]

Description

dryrun=True builds a full DryRunTracker (coverage, unsupported ops, engine count) and only prints it. There is no supported way to read those stats for CI or sweeps without monkeypatching.

Mark dryrun_stats_display with @observable() so callers can register on observers.pre / post and capture the tracker without a new public API.

Fixes # (issue)

Type of change

Please delete options that are not relevant and/or add your own.

• New feature (non-breaking change which adds functionality)

Checklist:

• [X ] My code follows the style guidelines of this project (You can use the linters)
• [ X] I have performed a self-review of my own code
• [ X] I have commented my code, particularly in hard-to-understand areas and hacks
• [X ] I have made corresponding changes to the documentation
• [ X] I have added tests to verify my fix or my feature
• [ X] New and existing unit tests pass locally with my changes
• [ X] I have added the relevant labels to my PR in so that relevant reviewers are notified

[micwill755]

Request changes, for these:

1. Docs missing. Checklist says docs were updated; they were not. Add the callback recipe to dryrun docs / observer docs.

2. Hook does not always run. dryrun_stats_display is skipped on some compile_module early returns including num_supported_ops == 0 even with dryrun=True. Coverage sweeps of unsupported models would get no tracker. Call display or emit the tracker on those paths too.

[micwill755]

dynamo.compile() needs an ExportedProgram, not an nn.Module. Export first with torch.export.export(model, (x,)), then pass that into compile.

Also drop enabled_precisions={torch.float32}, enabled_precisions is deprecated as of TRT 11. Dynamo uses dtypes on the model and input so this FP32 test needs no precision argument.