sdk-scheme-adapter support for test currencies XXX, XTS revoked with use of api-snippets

[elnyry-sam-k]

Summary:
The issue of support for test currencies XXX and XTS was resolved sometime ago (August 2020) in various services but when sdk-scheme-adapter was changed to use api-snippets instead of yaml files in this repo (around feb 2021), the support for these currencies seemed to have been removed, because these currencies are not included in api-snippets currency data model.

Notes:

1. Original issue that was fixed: Support test currencies XXX, XTS in ml-api-adapter #1652 in August 2020
2. Here's the ml-api-adapter release with that fix: https://github.com/mojaloop/ml-api-adapter/releases/tag/v11.0.3
3. Here's a PR by James on quoting service: Add ISO test currencies (XTS, XXX) quoting-service#238
4. Quoting service swagger (current snapshot): https://github.com/mojaloop/quoting-service/blob/0255b2f5869b7f0944c7834d51470afce3512281/src/interface/QuotingService-swagger.yaml#L750
5. sdk-scheme-adapter release with original fix: https://github.com/mojaloop/sdk-scheme-adapter/releases/tag/v11.1.1
6. sdk-scheme-adapter PR for the original issue: Add ISO-4217 test currencies to enable production testing scenarios. sdk-scheme-adapter#198
7. The issue: https://github.com/mojaloop/api-snippets/blob/master/fspiop/v1_1/openapi3/components/schemas/Currency.yaml - this doesn't have these test currencies (XXX, XTS)
8. It should've been fine till this release: https://github.com/mojaloop/sdk-scheme-adapter/releases/tag/v11.11.3

Severity:
High

Priority:
Critical

Expected Behavior

1. Send a quote/transfer where sdk-scheme-adapter is involved with test currencies XXX or XTS
2. Quotes and transfers should work fine without any issue (since these currencies should be allowed)

Steps to Reproduce

1. Send a quote/transfer where sdk-scheme-adapter is involved with test currencies XXX or XTS
2. Transfer should fail schema validation in sdk-scheme-adapter (simulator logs)

Specifications

• Component (if known): sdk-scheme-adapter
• Version: v11.18.8
• Platform: any
• Subsystem: api-snippets
• Type of testing: reported by an implementation team (Siva C)
• Bug found/raised by: @elnyry-sam-k

Notes:

• Severity when opened: High
• Priority when opened: Critical

[sivachundur]

Added missing currencies XTS & XXX to "api-snippets" which are part of ISO 4217
here is the PR for fixing it mojaloop/api-snippets#115

These needs to be added in the "sdk-scheme-adapter"
and here is the PR for it mojaloop/sdk-scheme-adapter#287

[sivachundur]

Fix is included in the sdk-scheme-adapter release version v11.18.9
https://github.com/mojaloop/sdk-scheme-adapter/releases/tag/v11.18.9

This SDK release will be testing in "product-qa" env tomorrow.

[elnyry-sam-k]

Thanks @sivachundur and @kleyow for the support and getting this done..

Great work!