Fix current validation errors.

[langfr]

TaxCategory ws null now at a couple of tests.
Fall back to the default implementation in the interface to fill the gap.

Open failures then:

[ERROR]   LibraryTest.testMinimumProfileValidityCreditNote:280 [XPath "count(//error)" evaluated to value] expected:<[0]> but was:<[1]>
[ERROR]   LibraryTest.testMinimumProfileValidityInvoice:256 [XPath "count(//error)" evaluated to value] expected:<[0]> but was:<[1]>

    <messages>
      <error type="4" location="/*[local-name()='CrossIndustryInvoice']/*[local-name()='SupplyChainTradeTransaction']/*[local-name()='ApplicableHeaderTradeAgreement']/*[local-name()='BuyerTradeParty']/*[local-name()='SpecifiedLegalOrganization']/*[local-name()='ID']" criterion="document('FACTUR-X_MINIMUM_codedb.xml')//cl[@id=5]/enumeration[@value=$codeValue5]">Value of '@schemeID' is not allowed. from /xslt/ZF_221/FACTUR-X_MINIMUM.xslt)</error>
    </messages>

Set attribute schemeID for a LegalOrganisation only, if not minimum profile. Otherwise only the id value.