fix(handles): Prepare for removal of IFluidHandleInternal.bind

[markfields]

Description

This function was deprecated in #24553 and its removal is tracked by #24557.

This PR addresses these last two usages:

• Updated some weird old tests that were calling bind on a DataStore's handle
• FluidObjectHandle.bind implementation, which included tracking pending handles and such. Copied this up to SharedObjectHandle where it belongs. All that logic will be removed from FluidObjectHandle when bind is removed.
• In some DDS tests we test or do serialization, with no interest in handle binding. But the FluidSerializer implementation requires a valid bind source. So add on a dummy bind function. (right now this is a no-op since all handles have a bind function, but once those are removed this still needs to work)

[Copilot]

Pull Request Overview

This PR removes deprecated usages of IFluidHandleInternal.bind by eliminating legacy binding calls in tests and refactoring the attachment logic in Fluid handle implementations. Key changes include:

• Updating end-to-end tests in attachRegisterLocalApiTests.spec.ts to replace bind calls with attachGraph.
• Adding legacy flow comments in FluidObjectHandle to clarify the temporary binding logic.
• Refactoring SharedObjectHandle to incorporate a pending handles mechanism and new attachGraph logic.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
packages/test/test-end-to-end-tests/src/test/attachRegisterLocalApiTests.spec.ts	Removed deprecated bind calls and updated variable naming via destructuring for clarity
packages/runtime/datastore/src/fluidHandle.ts	Added inline comments to mark the legacy bind/attach flow
packages/dds/shared-object-base/src/handle.ts	Refactored attachment logic with new isVisible getter, pendingHandles mechanism, and updated bind method

Comments suppressed due to low confidence (2)

packages/test/test-end-to-end-tests/src/test/attachRegisterLocalApiTests.spec.ts:539

• [nitpick] The renaming from 'peerDataStore' to 'dataStore2' improves readability. Please ensure the same naming convention is consistently applied across other similar tests.

				const { peerDataStore: dataStore2 } = await createPeerDataStore(

packages/dds/shared-object-base/src/handle.ts:104

• [nitpick] Consider adding more detail to the comment or documentation for the 'isVisible' getter to clarify its intended behavior in various attachment scenarios.

		if (this.isVisible) {

[agarwal-navin]

These tests are strange as in they use internal constructs like bind and attachGraph in an end-to-end test which isn't what an application would do.
I would consider removing these tests or at least not doing this via internal functions. For instance, instead of calling attachGraph() here, dataStore2's handle can be stored in the defaultDataStore's DDS.

[agarwal-navin]

Doesn't have to be in this PR of course. But these tests don't seem valuable to me.

[markfields]

Yeah they're totally weird! And some of it was just wrong, at least in comments. The changes here were just to remove the spurious bind calls and some minor clean ups I made while trying to follow along.

[agarwal-navin]

Agreed. I will create a work item to delete / update them.

[agarwal-navin]

Looks good. I left a comment on removing or updating the tests that used bind.

[markfields]

Waiting to merge until I get a clean run of the partner integration pipeline for test/remove-handle-bind-fn which includes this change as well as actually deleting all implementations of IFluidHandleInternal.bind outside of SharedObjectHandle.