Define plugin and chainloader deps in own dir

Just like we already did for the plugin host.

src/chainloader/meson.build

@@ -1,6 +1,14 @@
 # Like for the other libraries, the actual `shared_library()` call is in the
 # main `meson.build` file so everything gets bundled to a single directory.
 
+chainloader_deps = [
+  configuration_dep,
+
+  dl_dep,
+  ghc_filesystem_dep,
+  rt_dep,
+]
+
 vst2_chainloader_sources = files(
   '../common/logging/common.cpp',
   '../common/linking.cpp',