9919e92022cmake: Add optional sources to `minisketch` library directly (Hennadii Stepanov) Pull request description: This PR is a continuation of https://github.com/bitcoin/bitcoin/pull/31268 and applies similar changes to the `minisketch` library, which addresses [this comment](https://github.com/bitcoin/bitcoin/pull/30911#discussion_r1953081930). Additionally, a [workaround](https://github.com/bitcoin/bitcoin/blob/db36a92c02b83f2e6477a5a55fc061319f7cc6a3/cmake/minisketch.cmake#L77-L78) for a CMake bug has been removed. ACKs for top commit: theuni: utACK9919e92022Tree-SHA512: e41618ad6420d3e81960a4691d28b6c143c335e10edcae207cfc1e7743cf85aeab46ae495a5434469f45518db65cd8c18dc4d7815993e6d35aaf2abdcdb43f6b