demostanis

@MacDue: What do you recommend? Should I use AK::String instead of char**?

Hope this looks better now. It also depends on #14687.

Now using StringView instead of char*, Core::Stream instead of FILE*, ssize_t instead of unsigned long long and file->write instead of fprintf.

(still requires #14687, hence the CI fails..)

Where have my modifications gone

I gotta finish some examples in the man page and then I'll commit it

When comparing output of GNU coreutils' uniq to my version, I realized the field splitting isn't done correctly. Fields are ``, while I was doing ``. I fixed it.

Also added a man page.

#14718 was merged, the CI should pass, how do I retrigger it?

Some people don't like the grey background, so that might be removed from this PR. The synopsis shouldn't be indented, but that might require some more work.