perf data: Support using -f to override perf.data file ownership for 'convert'

Enable perf data convert to use perf.data when it is not owned by
current user or root.

Example:

 # perf record ls
 # chown Yunlong.Song:Yunlong.Song perf.data
 # ls -al perf.data
 -rw------- 1 Yunlong.Song Yunlong.Song 28260 Apr  2 17:35 perf.data
 # id
 uid=0(root) gid=0(root) groups=0(root),64(pkcs11)

Before this patch:

 # perf data convert --to-ctf=./ctf-data/
 File perf.data not owned by current user or root (use -f to override)
 # perf data convert --to-ctf=./ctf-data/ -f
   Error: unknown switch `f'

  usage: perf data convert [<options>]

     -v, --verbose         be more verbose
     -i, --input <file>    input file name
         --to-ctf ...      Convert to CTF format

After this patch:

 # perf data convert --to-ctf=./ctf-data/
 File perf.data not owned by current user or root (use -f to override)
 # perf data convert --to-ctf=./ctf-data/ -f
 # ls ctf-data/
 metadata  perf_stream_0

As shown above, the -f option...