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/unit/unit1608.c

@@ -30,25 +30,21 @@
 CURLcode Curl_shuffle_addr(struct Curl_easy *data,
                            struct Curl_addrinfo **addr);
 
-#define NUM_ADDRS 8
-static struct Curl_addrinfo addrs[NUM_ADDRS];
+static struct Curl_addrinfo addrs[8];
 
-static CURLcode unit_setup(void)
+static CURLcode t1608_setup(void)
 {
-  int i;
-  for(i = 0; i < NUM_ADDRS - 1; i++) {
+  size_t i;
+  for(i = 0; i < CURL_ARRAYSIZE(addrs) - 1; i++) {
     addrs[i].ai_next = &addrs[i + 1];
   }
 
   return CURLE_OK;
 }
 
-static void unit_stop(void)
+static CURLcode test_unit1608(char *arg)
 {
-  curl_global_cleanup();
-}
-
-UNITTEST_START
+  UNITTEST_BEGIN(t1608_setup())
 
   int i;
   CURLcode code;
@@ -73,17 +69,15 @@ UNITTEST_START
 
   abort_unless(addrhead != addrs, "addresses are not being reordered");
 
-UNITTEST_STOP
+  UNITTEST_END(curl_global_cleanup())
+}
 
 #else
-static CURLcode unit_setup(void)
+
+static CURLcode test_unit1608(char *arg)
 {
-  return CURLE_OK;
+  UNITTEST_BEGIN_SIMPLE
+  UNITTEST_END_SIMPLE
 }
-static void unit_stop(void)
-{
-}
-UNITTEST_START
-UNITTEST_STOP
 
 #endif