cksum: Handle args by clap 4 except for confliction

[oech3]

cksum is manually handling many flags and too complex.

[oech3]

@RenjiSann

[RenjiSann]

The flags that are handled manually are on purpose, to have the exact same behavior as GNU.

[oech3]

Needs other library to do same things?

[oech3]

I guess recient few clap PRs produced some dead objects

[oech3]

Is there any simple way to force-put --untagged on clap managed args?
Setting default value does not do what I expect.

[oech3]

Should we move clap arg chain to 1 .rs file before/at #10082 too?
Also I'm worring about binary size by individual *.ftl s .

[oech3]

Oh you already made https://github.com/uutils/coreutils/pull/10082/files#diff-def809ee2cee02c73b5de9299b74704952836901d9e67c2dd7129bc26a35213f