There is currently no way to see what user executed a watch. This commit
adds the decrypted username to each execution in the watch history, in a
new field "user".
Closes#31772
Each test now has its own watch id that is being used.
This ensures there are no old history entries, which can potentially
lead to broken test assertions.
This commit makes x-pack a module and adds it to the default
distrubtion. It also creates distributions for zip, tar, deb and rpm
which contain only oss code.
