refactor(core): Reorganizing internal/exported utils

[szanata]

Summary

• Consolidated ./utils and ./internal_utils under ./helpers (#helpers/* import). This module is organized in sub files, to allow tree-shaking imports;
• Added new Objects namespace to sdk/helpers, as those are used by other SDK modules. Added re-exports of the internal helpers;
• Removed core export ./sdk_utils altogether;
• Removed allSettledWithTimeout function, as it was not being used.

Test plan

• Added unit tests;
• Added contract tests;
• Manual run;

[bnchrch]

Nice follow-up. Splitting the utils grab-bag into themed #helpers/* files (tree-shakeable) and exposing a curated Objects on sdk/helpers is clean, and dropping ./sdk_utils closes the loop from #270. One real design question on the metadata write side, plus a sandbox-boundary note, inline.

[bnchrch]

❓ Dropping setMetadata means each factory now open-codes assignImmutableProperty( wrapper, METADATA_ACCESS_SYMBOL, ... ) and imports the symbol (here, plus evaluator.js, workflow.js, internal_activities x2). The read side (ComponentMetadata.has/getName) still hides the symbol, so reads and writes are now asymmetric and the symbol leaks to 5 spots. assignImmutableProperty is a nice generic, but WDYT about a thin domain writer over it that pairs with the reader, e.g. ComponentMetadata.set( fn, attrs ) (or setComponentMetadata)? Keeps the symbol and the immutability in one place.

[szanata]

I have added a new helper function to create the component, which encapsulates better the behavior.

[bnchrch]

🤔 workflow.js imports #helpers/object, so #helpers modules get bundled into the Temporal workflow sandbox, the same sandbox-safe constraint the sdk/helpers README spells out, but nothing says so for #helpers. shuffleArray's Math.random() is harmless today (only worker-side callers), but it's exactly what that guardrail catches. Worth a line that #helpers modules reachable from workflow code must stay sandbox-safe? (Minor aside: "helpers" now names two things, internal #helpers/* and exposed ./sdk/helpers, fine since the prefix disambiguates, just noting it after #270.)

[szanata]

I honestly think that it goes without saying, because the code doesnt even starts if you import stuff that Temporal considers non-deterministic, hence why I opted for the tree shaking method.

I made it extra clear on the sdk/helpers because those will be read elsewhere.

[bnchrch]

One idea is we have an explicit temporal-sandbox directory for any files that are meant to be sandbox safe.

but thats a very minor idea and out of scope a bit. not blocking