fix: normalized token address before the payment token comparison

[lwin-kyaw]

Explanation

This PR addresses ~

• Normalize payment token address comparison in SubscriptionController#getCryptoApproveTransactionParams.
• Prevent valid mixed-case or checksummed payment token addresses from being rejected when building approve transaction params.
• Add regression coverage for case-insensitive payment token matching.

Testing

• yarn workspace @metamask/subscription-controller run changelog:validate
• Jest not rerun in this pass

References

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

Low Risk
Low risk: a small change to token-address matching when building crypto approve params, plus a targeted regression test; only behavior change is accepting mixed-case/checksummed addresses that previously errored.

Overview
Fixes SubscriptionController#getCryptoApproveTransactionParams to normalize payment token address comparisons (lowercasing both sides) so mixed-case/checksummed token addresses no longer fail with "Invalid token address".

Adds a Jest regression test covering case-insensitive token matching, and records the change in the @metamask/subscription-controller changelog.

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