feat: Add Rokt close implementation

[jamesnrokt]

Instructions

1. PR target branch should be against development
2. PR title name should follow this format: https://github.com/mParticle/mparticle-workflows/blob/main/.github/workflows/pr-title-check.yml
3. PR branch prefix should follow this format: https://github.com/mParticle/mparticle-workflows/blob/main/.github/workflows/pr-branch-check-name.yml

Summary

• Add Rokt close implementation

Testing Plan

• N/A

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

• Closes https://go.mparticle.com/work/SQDSDKS-7445

[Copilot]

Pull Request Overview

This PR adds a close method implementation for the Rokt kit to cleanly shut down the SDK.

• Introduces - (MPKitExecStatus *)close in MPKitRokt.m
• Calls [Rokt close] and returns a success status

Comments suppressed due to low confidence (2)

mParticle-Rokt/MPKitRokt.m:418

• The new close method isn't declared in the MPKitRokt.h header, so it won't be exposed to callers. Please add its declaration to the kit's public interface.

- (MPKitExecStatus *)close {

mParticle-Rokt/MPKitRokt.m:418

• [nitpick] There's no test coverage for the new close implementation. Consider adding a unit test to verify that [Rokt close] is called and the MPKitExecStatus is returned correctly.

- (MPKitExecStatus *)close {