curl: make %output{} in -w specify a file to write to

It can be used multiple times. Use %output{>>name} to append.

Add docs. Test 990 and 991 verify.

Idea: #11400
Sugg

curl: make %output{} in -w specify a file to write to

It can be used multiple times. Use %output{>>name} to append.

Add docs. Test 990 and 991 verify.

Idea: #11400
Suggested-by: ed0d2b2ce19451f2
Closes #11416

show more ...