Create PosSystem migration guide

[deboragracio]

• You've read the Contributor Guide and Code of Conduct.
• You've included unit or integration tests for your change, where applicable.
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• There's an open issue for the PR that you are making. If you'd like to propose a new feature or change, please open an issue to discuss the change or find an existing issue.

Description

Details can be found on https://github.com/fiskaltrust/engineering/issues/1116

[github-actions]

✅ CLA Signed

All contributors have signed the CLA. Thank you!

[deboragracio]

I have read the CLA Document and I hereby sign the CLA

[LGuichet]

• Review the content (bullet points) under the Introduction and Prerequisites sections for accuracy.

• Under Prerequisites, confirm whether the caution note “Market availability” is correct and relevant here. If so, please confirm whether there is any constraints for Germany (DE).

• 3. Confirm whether the Architecture Overview section is relevant here, as well as its content is accurate.

• 4. Review the content of the Cloud CheckBox (base URL change) section.

• 5. Review the content of the Case Values section. Before updating the v2 values used for ftReceiptCase, ftChargeItemCase, and ftPayItemCase, I want to confirm whether we should list them directly on this new page or simply refer the https://github.com/fiskaltrust/service-possystem-api/blob/main/doc/mapping-v2-v0/readme.md file. Note that if we decide to list them directly in the guide, we must keep them synchronized whenever updates are made to the .md file, and also make it public. This is the format I would use to display them on the docs page:

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• 6. In the .md file, I can see that ftSignatureType and ftState are listed for each market. Should we include them under Case Values as well?

• 7. Review the content of the following sections: ftReceiptCaseData Format, ReceiptRequest, ReceiptResponse, and Timestamps.

• 8. Review the content of the Local CashBox section.

• 9. Confirm whether the API changes section is relevant for this guide.

[arnaud-chentil]

I have read the CLA Document and I hereby sign the CLA