Merge pull request #39647 (Add KMyMoney)

This adds KMyMoney, a finance manager for KDE plus a few required
dependencies.

I ran the upstream test suite as well as the following manual tests:

  * Basic startup
  * Completing the wizard
  * Add some test transactions
  * GPG encryption
  * Generation of charts and reports
  * Rough check whether OFX integration lists supported financial
    institutions.
  * Small check of AqBanking implementation, whether accounts and users
    can be configured, but didn't test actual connectivity with a
    financial institution.
  * Check of Weboob integration with a test PayPal backend, however also
    just with a dummy account and without actually connecting to PayPal.

On top of that, the application already is being used by the person
requesting me to package this, so I'd guess it works well enough.

I'm merging this without the review from @ttuegel because it only adds
packages and doesn't change anything fundamental about the KDE
ecosystem.

The only change here is to add C++ support to "mpir", where the
maintainer (@7c6f434c) has approved the change.