build: enable -Wformat-signedness, fix issues found

Adjust code to avoid `-Wformat-signedness` warnings, while making sure
that enums are always cast to a known type when passing them to `printf`
functions, to support compilers and compiler settings where enums are
not default-size signed ints.

- cast integers printed as hex to `unsigned`. (63 times, 20 of them in
  `mbedtls.c`)
- cast misc enums to `int` for printing. (31 times)
- cast `CURL_LOCK_DATA_*` enums to `int`. (4 times)
- cast `CURL_FORMADD_*` enums to `int`. (13 times)
- cast `CURLSHE_*` enums to `int`. (3 times)
- cast `CURLUE_*` enums to `int`. (33 times)
- cast `CURLMSG_*` enums to `int`. (6 times)
- cast `CURLE_*` enums to `int`. (~380 times)
- unit1675: fix mask.
  Follow-up to 7c34365cce #21879

Ref: #18343 (initial attempt)

Closes #20848

lib/cf-https-connect.c

@@ -575,7 +575,7 @@ static CURLcode cf_hc_connect(struct Curl_cfilter *cf,
   }
 
 out:
-  CURL_TRC_CF(data, cf, "connect -> %d, done=%d", result, *done);
+  CURL_TRC_CF(data, cf, "connect -> %d, done=%d", (int)result, *done);
   return result;
 }
 
@@ -615,7 +615,7 @@ static CURLcode cf_hc_shutdown(struct Curl_cfilter *cf,
         result = ctx->ballers[i].result;
     }
   }
-  CURL_TRC_CF(data, cf, "shutdown -> %d, done=%d", result, *done);
+  CURL_TRC_CF(data, cf, "shutdown -> %d, done=%d", (int)result, *done);
   return result;
 }
 
@@ -634,7 +634,8 @@ static CURLcode cf_hc_adjust_pollset(struct Curl_cfilter *cf,
         continue;
       result = Curl_conn_cf_adjust_pollset(b->cf, data, ps);
     }
-    CURL_TRC_CF(data, cf, "adjust_pollset -> %d, %u socks", result, ps->n);
+    CURL_TRC_CF(data, cf, "adjust_pollset -> %d, %u socks", (int)result,
+                ps->n);
   }
   return result;
 }