refactor: migrate filteredMparticleUser module to TS

[jaissica12]

Background

• Continuing the effort to migrate remaining JavaScript modules in the mParticle Web SDK to TypeScript for improved type safety and developer experience. filteredMparticleUser.js was one of the remaining JS modules used by forwarders and Rokt filtered-user construction.

What Has Changed

• Converted src/filteredMparticleUser.js to src/filteredMparticleUser.ts with type annotations
• Added IFilteredMparticleUser interface
• Filtering logic for identities/attributes is preserved
• No intentional public API or functional changes

Screenshots/Video

• N/A

Checklist

• I have performed a self-review of my own code.
• I have made corresponding changes to the documentation.
• I have added tests that prove my fix is effective or that my feature works.
• I have tested this locally.

Additional Notes

• No dedicated unit/integration tests exist specifically for this module
• getAllUserAttributes is referenced via a local function so the module typechecks when invoked without new (same call pattern as production call sites)

Reference Issue (For employees only. Ignore if you are an outside contributor)

• Closes https://go/j/SDKE-1193

[cursor]

PR Summary

Low Risk
Mechanical TypeScript migration with preserved filtering logic; no new runtime paths beyond typing and a structural refactor of getAllUserAttributes.

Overview
Migrates filteredMparticleUser from JavaScript to TypeScript by removing filteredMparticleUser.js and adding filteredMparticleUser.ts, with no intended behavior change for forwarders and Rokt filtered-user construction.

The factory and returned object are now typed via IFilteredMparticleUser, with parameters annotated (MPID, MPForwarder / partial forwarder shape, IMParticleWebSDKInstance, optional KitBlocker). getAllUserAttributes is implemented as a local function referenced on the returned object (instead of closing over self), matching existing call sites that invoke the factory without new. Helper calls on _Helpers use casts so filterUserAttributes and filterUserIdentitiesForForwarders still compile against loosely typed internals.

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[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[rmi22186]

Tests: unchanged (no test/ files).

Request: add filterUserAttributes / filterUserIdentitiesForForwarders to SDKHelpersApi and call them typed, instead of:

((mpInstance._Helpers as Dictionary).filterUserAttributes as Function)(...)

Those casts undo most of the typing win from the migration.

Union MPForwarder | { userAttributeFilters: number[] } is fine for the Rokt path; a tiny shared filter-config type would be cleaner but optional.

Merge this before #1336 (already approved).

[alexs-mparticle]

We should have an IHelpersAPI interface or something similar that can be used here.