Revert "feat: Add PaymentExtension-to-Mono-Repo"

[BrandonStalnaker]

We want the Payment Extension to be part of the Rokt monorepo (planned) rather than the mParticle repo
Reverts #776

[cursor]

PR Summary

Medium Risk
Changes RoktSDKPlus SPM/CocoaPods resolution and release/mirror behavior for Rokt packages; wrong pins or mirror config could break Shoppable Ads integrations until consumers use external RoktPaymentExtension 2.x.

Overview
This reverts bringing Rokt Payment Extension into the mParticle monorepo: the whole Kits/rokt-payment-extension/rokt-payment-extension-ios tree (sources, tests, podspec, docs) is removed, and Kits/matrix.json drops the rokt-payment-extension-ios kit plus related RoktSDKPlus matrix flags (mirror_force_push_main, payment-extension pod lint includes).

RoktSDKPlus again depends on the external ROKT/rokt-payment-extension-ios on its 2.x line (Package.swift pins ~> 2.0.2; RoktSDKPlus.podspec uses RoktPaymentExtension '~> 2.0' instead of matching ecosystem semver). Docs state payment extension versioning is separate from mParticle/RoktSDKPlus releases.

CI/release is trimmed: pod lint always includes core podspecs (no standalone kit path); release draft no longer bumps payment-extension Package.swift; publish drops force-push mirroring, RoktPaymentExtension CocoaPods CDN wait, and payment-extension mirror notes in RELEASE.md.

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[github-actions]

📦 SDK Size Impact Report

Measures how much the SDK adds to an app's size (with-SDK minus without-SDK).

Metric	Target Branch	This PR	Change
App Bundle Impact	1.77 MB	1.77 MB	+N/A
Executable Impact	848 bytes	848 bytes	+N/A
XCFramework Size	6.45 MB	6.45 MB	+N/A

➡️ SDK size impact change is minimal.

Raw measurements

Target branch (main):

{"baseline_app_size_kb":84,"baseline_executable_size_bytes":75464,"with_sdk_app_size_kb":1900,"with_sdk_executable_size_bytes":76312,"sdk_impact_kb":1816,"sdk_executable_impact_bytes":848,"xcframework_size_kb":6604}

This PR:

{"baseline_app_size_kb":84,"baseline_executable_size_bytes":75464,"with_sdk_app_size_kb":1900,"with_sdk_executable_size_bytes":76312,"sdk_impact_kb":1816,"sdk_executable_impact_bytes":848,"xcframework_size_kb":6604}