Add a flag that enables all linting

[szymon-rd]

Having a flag enabling all the linting options at once would be helpful. More and more linting is being added, and writing all the flags can make the compile command long. It is also a standard user path to enable all the linting options.

[som-snytt]

The topic of research is what to name it.

I previously tried legacy -Xlint #14753

Conforming -Wlint isn't pronounceable.

Maybe there is a linguist at EPFL.

[SethTisue]

fwiw, gcc uses -Wall (and has for donkey's years)

[som-snytt]

I happen to be reading Moby-Dick, -Wal.

[Linyxus]

closed by #20577