This reverts commit a7a55fb3ac4f7f8b6dd97fa51b4f2cd21a871022, turns out there's still work to be done before that dependency can be dropped
it also:
* removes redundant target_link_libraries calls related to the wallet <-> server circular dependency
* removes a libevent dependency from wallet since the only function that needed it was moved to src/util/url.cpp
* added an explicit libevent dependency to util, and moved the code that finds libevent to account for that
Depends on D6256