race condition in libprocessgroup

while enable fdsan (file descriptor sanitizer),
fdsan report use-after-close error after boot complete (sedom).

Because, in SetCgroupAction::EnableResourceCaching() currently has a data race against all the
use fd_ functions like SetCgroupAction::ExecuteForProcess(uid_t uid, pid_t pid) etc.

ThreadA                                     | ThreadB
-------------------------------------------------------------------------------------------------
in SetCgroupAction::EnableResourceCaching() | in SetCgroupAction::ExecuteForProcess(...)
-------------------------------------------------------------------------------------------------
                                            | in SetCgroupAction::AddTidToCgroup(int tid, int fd)
-------------------------------------------------------------------------------------------------
fd_ = std::move(fd); /*modified fd_ value*/ |
-------------------------------------------------------------------------------------------------
                                            | write(fd)  /* crash here, fd is closed by ThreadA*/
-------------------------------------------------------------------------------------------------

So, add mutex lock to protect fd_ data race.

Bug: 134120826
Test: auto test, run the adb reboot test 100 times and no fdsan error report on libprocessgroup
Merged-In: Iccf2f705e030f79324f1164509e715dc5be825de
Change-Id: Iccf2f705e030f79324f1164509e715dc5be825de