cleanup: Map test files according to structure in src

For example cmd_account() is located in src/command/cmd_funcs.c.
The unit test was located in tests/unittests/test_cmd_account.c.
Let's move it to a subdirectory like tests/unittests/command/test_cmd_account.c
to correpsond to the same structure.

tests/unittests/xmpp/test_muc.c

@@ -0,0 +1,87 @@
+#include "prof_cmocka.h"
+#include <stdlib.h>
+
+#include "xmpp/muc.h"
+
+void prof_shutdown(void);
+
+int
+muc_before_test(void** state)
+{
+    muc_init();
+    return 0;
+}
+
+int
+muc_after_test(void** state)
+{
+    prof_shutdown();
+    return 0;
+}
+
+void
+test_muc_invites_add(void** state)
+{
+    char* room = "room@conf.server";
+    muc_invites_add(room, NULL);
+
+    gboolean invite_exists = muc_invites_contain(room);
+
+    assert_true(invite_exists);
+}
+
+void
+test_muc_remove_invite(void** state)
+{
+    char* room = "room@conf.server";
+    muc_invites_add(room, NULL);
+    muc_invites_remove(room);
+
+    gboolean invite_exists = muc_invites_contain(room);
+
+    assert_false(invite_exists);
+}
+
+void
+test_muc_invites_count_0(void** state)
+{
+    int invite_count = muc_invites_count();
+
+    assert_true(invite_count == 0);
+}
+
+void
+test_muc_invites_count_5(void** state)
+{
+    muc_invites_add("room1@conf.server", NULL);
+    muc_invites_add("room2@conf.server", NULL);
+    muc_invites_add("room3@conf.server", NULL);
+    muc_invites_add("room4@conf.server", NULL);
+    muc_invites_add("room5@conf.server", NULL);
+
+    int invite_count = muc_invites_count();
+
+    assert_true(invite_count == 5);
+}
+
+void
+test_muc_room_is_not_active(void** state)
+{
+    char* room = "room@server.org";
+
+    gboolean room_is_active = muc_active(room);
+
+    assert_false(room_is_active);
+}
+
+void
+test_muc_active(void** state)
+{
+    char* room = "room@server.org";
+    char* nick = "bob";
+    muc_join(room, nick, NULL, FALSE);
+
+    gboolean room_is_active = muc_active(room);
+
+    assert_true(room_is_active);
+}