text-utils: add bits command

text-utils: add bits command

Add a new text utility to convert bit masks in various formats.

This can be handy to avoid parsing affinity masks in one's head and/or
to interact with the kernel in a more human friendly way. It is
a rewrite in C of the bits command from my linux-tools python package so
that it can be more widely available.

Here is an example:

 ~# cat /sys/kernel/debug/tracing/tracing_cpumask
 ffffffff,ffffffff,ffffffff,ffffffff
 ~# bits -l ,$(cat /sys/kernel/debug/tracing/tracing_cpumask)
 0-128
 ~# bits -g 58,59,120,123
 9000000,00000000,0c000000,00000000
 ~# bits -g 58,59,120,123 > /sys/kernel/debug/tracing/tracing_cpumask
 ~# echo 1 > /sys/kernel/debug/tracing/tracing_on

Add man page and basic tests.

Link: https://git.sr.ht/~rjarry/linux-tools#bits
Signed-off-by: Robin Jarry <robin@jarry.cc>