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/unit1305.c

@@ -40,24 +40,17 @@
 
 #include "memdebug.h" /* LAST include file */
 
-static struct Curl_easy *t1305_easy;
 static struct Curl_dnscache hp;
 static char *data_key;
 static struct Curl_dns_entry *data_node;
 
-static CURLcode unit_setup(void)
+static CURLcode t1305_setup(void)
 {
-  t1305_easy = curl_easy_init();
-  if(!t1305_easy) {
-    curl_global_cleanup();
-    return CURLE_OUT_OF_MEMORY;
-  }
-
   Curl_dnscache_init(&hp, 7);
   return CURLE_OK;
 }
 
-static void unit_stop(void)
+static void t1305_stop(void)
 {
   if(data_node) {
     Curl_freeaddrinfo(data_node->addr);
@@ -65,15 +58,12 @@ static void unit_stop(void)
   }
   free(data_key);
   Curl_dnscache_destroy(&hp);
-
-  curl_easy_cleanup(t1305_easy);
-  curl_global_cleanup();
 }
 
 static struct Curl_addrinfo *fake_ai(void)
 {
   static struct Curl_addrinfo *ai;
-  static const char dummy[]="dummy";
+  static const char dummy[] = "dummy";
   size_t namelen = sizeof(dummy); /* including the null-terminator */
 
   ai = calloc(1, sizeof(struct Curl_addrinfo) + sizeof(struct sockaddr_in) +
@@ -109,14 +99,15 @@ static CURLcode create_node(void)
   return CURLE_OK;
 }
 
-
-UNITTEST_START
+static CURLcode test_unit1305(char *arg)
+{
+  UNITTEST_BEGIN(t1305_setup())
 
   struct Curl_dns_entry *nodep;
   size_t key_len;
 
   /* Test 1305 exits without adding anything to the hash */
-  if(strcmp(arg, "1305") != 0) {
+  if(testnum == 1306) {
     CURLcode rc = create_node();
     abort_unless(rc == CURLE_OK, "data node creation failed");
     key_len = strlen(data_key);
@@ -128,4 +119,5 @@ UNITTEST_START
     data_node = NULL;
   }
 
-UNITTEST_STOP
+  UNITTEST_END(t1305_stop())
+}