treewide: fix typos and other minor issues

tests/external.nix

@@ -430,9 +430,9 @@
         # fetchmail returns EXIT_CODE 0 when it retrieves mail
         client.succeed("fetchmail --nosslcertck -v")
 
-    with subtest("catchAlls"):
+    with subtest("domain catch-all"):
         client.execute("rm ~/mail/*")
-        # send email from chuck to non exsitent account
+        # send email from chuck to non-existent account
         client.succeed(
             "msmtp -a test3 --tls=on --tls-certcheck=off --auth=on lol@example.com < /etc/root/email2 >&2"
         )
@@ -447,7 +447,7 @@
         )
         server.wait_until_fails('[ "$(postqueue -p)" != "Mail queue is empty" ]')
         # fetchmail returns EXIT_CODE 1 when no new mail
-        # if this succeeds, it means that user1 recieved the mail that was intended for chuck.
+        # if this succeeds, it means that user1 received the mail that was intended for chuck.
         client.fail("fetchmail --nosslcertck -v")
 
     with subtest("extraVirtualAliases"):

tests/ldap.nix

@@ -135,7 +135,7 @@ in
 
       # This function retrieves the ldap table file from a postconf
       # command.
-      # A key lookup is achived and the returned value is compared
+      # A key lookup is achieved and the returned value is compared
       # to the expected value.
       def test_lookup(postconf_cmdline, key, expected):
         conf = machine.succeed(postconf_cmdline).rstrip()