tests: always make bundles, adapt build and tests

Make test bundles the default. Drop non-bundle build mode.
Also do all the optimizations and tidy-ups this allows, simpler builds,
less bundle exceptions, streamlined build mechanics.

Also rework the init/deinit macro magic for unit tests. The new method
allows using unique init/deinit function names, and calling them with
arguments. This is in turn makes it possible to reduce the use of global
variables.

Note this drop existing build options `-DCURL_TEST_BUNDLES=` from cmake
and `--enable-test-bundles` / `--disable-test-bundles` from autotools.

Also:
- rename test entry functions to have unique names: `test_<testname>`
  This removes the last exception that was handled in the generator.
- fix `make dist` to not miss test sources with test bundles enabled.
- sync and merge `tests/mk-bundle.pl` into `scripts/mk-unity.pl`.
- mk-unity.pl: add `--embed` option and use it when `CURL_CLANG_TIDY=ON`
  to ensure that `clang-tidy` does not miss external test C sources.
  (because `clang-tidy` ignores code that's #included.)
- tests/unit: drop no-op setup/stop functions.
- tests: reduce symbol scopes, global macros, other fixes and tidy-ups.
- tool1621: fix to run, also fix it to pass.
- sockfilt: fix Windows compiler warning in certain unity include order,
  by explicitly including `warnless.h`.

Follow-up to 6897aeb105 #17468

Closes #17590

tests/tunit/tool1604.c

@@ -32,18 +32,7 @@
 
 #include "memdebug.h" /* LAST include file */
 
-static CURLcode unit_setup(void)
-{
-  return CURLE_OK;
-}
-
-static void unit_stop(void)
-{
-
-}
-
 #if defined(_WIN32) || defined(MSDOS)
-
 static char *getflagstr(int flags)
 {
   char *buf = malloc(256);
@@ -71,16 +60,21 @@ static char *getcurlcodestr(int cc)
   }
   return buf;
 }
+#endif
 
-struct data {
-  const char *input;
-  int flags;
-  const char *expected_output;
-  SANITIZEcode expected_result;
-};
+static CURLcode test_tool1604(char *arg)
+{
+  UNITTEST_BEGIN_SIMPLE
 
-UNITTEST_START
-{ /* START sanitize_file_name */
+#if defined(_WIN32) || defined(MSDOS)
+  struct data {
+    const char *input;
+    int flags;
+    const char *expected_output;
+    SANITIZEcode expected_result;
+  };
+
+  /* START sanitize_file_name */
   struct data data[] = {
     { "", 0,
       "", SANITIZE_ERR_OK
@@ -256,13 +250,10 @@ UNITTEST_START
     free(received_ccstr);
     free(expected_ccstr);
   }
-} /* END sanitize_file_name */
-
+  /* END sanitize_file_name */
 #else
-UNITTEST_START
-{
   fprintf(stderr, "Skipped test not for this platform\n");
-}
 #endif /* _WIN32 || MSDOS */
 
-UNITTEST_STOP
+  UNITTEST_END_SIMPLE
+}