Merge bitcoin/bitcoin#33853: kernel: Allow null arguments for serialized data

a3ac59a431 ci: Enable experimental kernel stuff in ASan task (MarcoFalke)
5b89956eeb kernel: Allow null arguments for serialized data (TheCharlatan)

Pull request description:

  An empty span constructed from an empty vector may have a null data pointer depending on the implementation. Remove the BITCOINKERNEL_ARG_NONNULL requirement for these arguments and instead handle such null arguments in the implementation.

  Also cherry-picked from #33845 to show that CI task passing now.

ACKs for top commit:
  yuvicc:
    Code review ACK a3ac59a431
  maflcko:
    review ACK a3ac59a431 🥈
  laanwj:
    code review ACK a3ac59a431

Tree-SHA512: 629e463796f2f057df5be8e8981a45751c578ed0021be731c1d57fe849a539fe38b0a445914b0fc48f32f0408ad6d566984bd7f3a68797fcfdf1c6889e316a08

ci/test/00_setup_env_native_asan.sh

@@ -26,7 +26,7 @@ export NO_DEPENDS=1
 export GOAL="install"
 export CI_LIMIT_STACK_SIZE=1
 export BITCOIN_CONFIG="\
- -DWITH_USDT=ON -DWITH_ZMQ=ON -DBUILD_GUI=ON \
+ --preset=dev-mode \
  -DSANITIZERS=address,float-divide-by-zero,integer,undefined \
  -DCMAKE_C_COMPILER=clang \
  -DCMAKE_CXX_COMPILER=clang++ \