app_server: fix test-app_server for launch_daemon changes

* Make test-app_server work again in a launch_daemon environment

* test_registrar gets a separate signature and port name again so the
host system can distinguish it from the system registrar

* AppServer is normally a BServer now, however, there can't be two
BApplications in one team. A class TestServerLoopAdapter is added,
which becomes the base class of AppServer instead of BServer when
compiling for libbe_test. It's an adapter class which looks towards
AppServer as it if was a BServer, but internally it is derived from
MessageLooper (like the old AppServer before the transition to
BServer).

This way, AppServer can stay a BServer in normal builds and it also
avoids having to use too many #ifdefs to distinguish the two
versions.

Get test_app_server to run again

* We should have the buildbots compile this to make sure it still works
* I had to split two ServerApp methods to a searate C++ file to link
them in libtestappserver.so
* some fixes related to the switch to PM and better hybrid support in
jam rules; moving of MIME stuff from registrar to storage kit, merge of
Locale Kit and ICU in libbe, and a few more.
* Modified the test_app_server hwinterface and rdef file so it is not a
background app, and the window isn't floating. Otherwise, hiding the
window would leave you without a way to recover it.

Get test_app_server to run again

* We should have the buildbots compile this to make sure it still works
* I had to split two ServerApp methods to a searate C++ file to link
them in libtestappserver.so
* some fixes related to the switch to PM and better hybrid support in
jam rules; moving of MIME stuff from registrar to storage kit, merge of
Locale Kit and ICU in libbe, and a few more.
* Modified the test_app_server hwinterface and rdef file so it is not a
background app, and the window isn't floating. Otherwise, hiding the
window would leave you without a way to recover it.