Expose `InstallmentsInfo` in `SubscriptionOption`

[tonidero]

Description

This exposes the info for installment plans so developers can use it. The new API looks like:

• New InstallmentsInfo interface with commitmentPaymentsCount and subsequentCommitmentPaymentsCount fields.
• New GoogleInstallmentsInfo data class implementing previous interface.
• New method in SubscriptionOption/GoogleSubscriptionOption exposing the installments info.

[RevenueCat-Danger-Bot]

	1 Message
:book:	Size increase: 8.10 KB

Generated by :no_entry_sign: Danger

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 90.90909% with 1 line in your changes missing coverage. Please review.

Please upload report for BASE (sdk-3465-support-bc7@ac81117). Learn more about missing BASE report.

Files	Patch %	Lines
...om/revenuecat/purchases/models/TestStoreProduct.kt	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## sdk-3465-support-bc7 #1724 +/- ## ======================================================= Coverage ? 83.13% ======================================================= Files ? 222 Lines ? 7558 Branches ? 1067 ======================================================= Hits ? 6283 Misses ? 851 Partials ? 424 ```

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