Inconsistent references to ISO 4217 currency codes

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The Activity and Organisation standards refer to ISO 4217 codes in 3 different ways between them:

• Alphabetic Currency Code: https://github.com/IATI/IATI-Schemas/blob/version-2.02/iati-activities-schema.xsd#L180 / https://github.com/IATI/IATI-Schemas/blob/version-2.02/iati-activities-schema.xsd#L2856
• Currency Code: https://github.com/IATI/IATI-Schemas/blob/version-2.02/iati-organisations-schema.xsd#L114 (could include the numeric codes that are not on the Codelist)
• Three Letter Code: https://github.com/IATI/IATI-Schemas/blob/version-2.02/iati-organisations-schema.xsd#L886 (could include the numeric codes that are not on the Codelist)

One way of referring to ISO 4217 codes should be chosen and utilised throughout the Schemas. The Codelist only contains alphabetic codes, so this should likely be the chosen solution.