Kernel+Userland: Replace the beep syscall with the new /dev/beep device

There's no need to have separate syscall for this kind of functionality,
as we can just have a device node in /dev, called "beep", that allows
writing tone generation packets to emulate the same behavior.

In addition to that, we remove LibC sysbeep function, as this function
was never being used by any C program nor it was standardized in any
way.
Instead, we move the userspace implementation to LibCore.

Userland/Libraries/LibC/unistd.cpp

@@ -925,12 +925,6 @@ int gettid()
     return cached_tid;
 }
 
-int sysbeep(int tone)
-{
-    int rc = syscall(SC_beep, tone);
-    __RETURN_WITH_ERRNO(rc, rc, -1);
-}
-
 // https://pubs.opengroup.org/onlinepubs/9699919799/functions/fsync.html
 int fsync(int fd)
 {

Userland/Libraries/LibC/unistd.h

@@ -36,7 +36,6 @@ int get_process_name(char* buffer, int buffer_size);
 int set_process_name(char const* name, size_t name_length);
 void dump_backtrace(void);
 int fsync(int fd);
-int sysbeep(int tone);
 int gettid(void);
 int getpagesize(void);
 pid_t fork(void);