all: change optional to result in most of the libraries (#16123)

vlib/crypto/rand/rand_windows.c.v

@@ -14,7 +14,7 @@ const (
 )
 
 // read returns an array of `bytes_needed` random bytes read from the OS.
-pub fn read(bytes_needed int) ?[]u8 {
+pub fn read(bytes_needed int) ![]u8 {
 	mut buffer := []u8{len: bytes_needed}
 	// use bcrypt_use_system_preferred_rng because we passed null as algo
 	status := C.BCryptGenRandom(0, buffer.data, bytes_needed, rand.bcrypt_use_system_preferred_rng)