Add Standalone Nexus Operation links

[Quinn-With-Two-Ns]

What was changed

Add Standalone nexus operation links

Why?

So SANO has nice links in the UI

Checklist

1. Closes

2. How was this tested:

3. Any docs updates needed?

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Note

Medium Risk
Changes how Nexus and workflow RPCs attach links (including completion callbacks), which affects UI correlation; behavior is well-tested but mistakes could drop or mis-route links across SANO, workflows, and signal-with-start.

Overview
Adds bidirectional link plumbing for standalone Nexus operations (SANO): the SDK now converts and forwards Link.NexusOperation alongside existing Link.WorkflowEvent links through the Nexus handler path.

LinkConverter gains nexusOperationToNexusLink / nexusLinkToNexusOperation (using temporal:///…/nexus-operations/…/details URLs), plus linkToNexusLink and nexusLinkToLink dispatchers. NexusTaskHandlerImpl, InternalUtils (Nexus-bound workflow start), and NexusStartWorkflowHelper are switched to these APIs so inbound SANO links attach to handler RPCs (e.g. signal-with-start) and response workflow-event links round-trip on StartOperationResponse.

Integration tests cover SANO ↔ backing-workflow links and SANO-triggered signal-with-start back/forward links (external server only). Unit coverage for Nexus operation URL encoding/parsing is in LinkConverterTest.

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