Remove libcompos_client

CompOS APEX no longer needs to provide libcompos_client API (added
recently during T development).

Some of the code is still reusable, so the remaining code is moved to
composd/src/fd_server_helper.rs.

Bug: 205750213
Test: m
Test: atest ComposHostTestCases

Change-Id: I584b700c41ffc0e08c6ac6c171cb17ab21c7d8ff
diff --git a/compos/composd/Android.bp b/compos/composd/Android.bp
index a76d96c..2ab12e3 100644
--- a/compos/composd/Android.bp
+++ b/compos/composd/Android.bp
@@ -18,6 +18,8 @@
         "libbinder_rs",
         "libcompos_common",
         "libcomposd_native_rust",
+        "libminijail_rust",
+        "libnix",
         "libnum_traits",
         "liblog_rust",
         "librustutils",