Add support for exporting SEPA XML files

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Minimal example file:

<?xml version="1.0" encoding="UTF-8" ?>
<Document 
  xmlns="urn:iso:std:iso:20022:tech:xsd:pain.001.001.03"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
  xsi:schemaLocation="urn:iso:std:iso:20022:tech:xsd:pain.001.001.03 pain.001.001.03.xsd"
>
  <CstmrCdtTrfInitn>
    <GrpHdr>
      <MsgId>JustATest123</MsgId>
      <CreDtTm>2022-08-26T14:45:57Z</CreDtTm>
      <NbOfTxs>1</NbOfTxs>
      <CtrlSum>1</CtrlSum>
      <InitgPty><Nm>Test GmbH</Nm></InitgPty>
    </GrpHdr>
    <PmtInf>
      <PmtInfId>Submitter123</PmtInfId>
      <PmtMtd>TRF</PmtMtd>
      <BtchBookg>false</BtchBookg>
      <NbOfTxs>1</NbOfTxs>
      <CtrlSum>1</CtrlSum>
      <PmtTpInf><SvcLvl><Cd>SEPA</Cd></SvcLvl></PmtTpInf>
      <ReqdExctnDt>2022-08-26</ReqdExctnDt>
      <Dbtr><Nm>Test GmbH</Nm></Dbtr>
      <DbtrAcct><Id><IBAN>DExxxxxxxxxx</IBAN></Id></DbtrAcct>
      <DbtrAgt><FinInstnId><BIC>BANKXXXXXXX</BIC></FinInstnId></DbtrAgt>
      <ChrgBr>SLEV</ChrgBr>
      <CdtTrfTxInf>
        <PmtId><EndToEndId>NOTPROVIDED</EndToEndId></PmtId>
        <Amt><InstdAmt Ccy="EUR">1.00</InstdAmt></Amt>
        <Cdtr><Nm>John Doe</Nm></Cdtr>
        <CdtrAcct><Id><IBAN>DEyyyyyyy</IBAN></Id></CdtrAcct>
        <Purp><Cd>53</Cd></Purp>
        <RmtInf><Ustrd>Test Transaction</Ustrd></RmtInf>
      </CdtTrfTxInf>
    </PmtInf>
  </CstmrCdtTrfInitn>
</Document>