all: fix typos in comments

Fix its/it's, who's/whose, wether/whether, missing apostrophes
in contractions, and other misspellings across the codebase.

Updates #cleanup

Change-Id: I20453b81a7aceaa14ea2a551abba08a2e7f0a1d8
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

net/socks5/socks5_test.go

@@ -222,7 +222,7 @@ func TestUDP(t *testing.T) {
 		if err != nil {
 			t.Fatal(err)
 		}
-		_, err = conn.Write(append([]byte{socks5Version, byte(udpAssociate), 0x00}, targetAddrPkt...)) // client reqeust
+		_, err = conn.Write(append([]byte{socks5Version, byte(udpAssociate), 0x00}, targetAddrPkt...)) // client request
 		if err != nil {
 			t.Fatal(err)
 		}