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/server/getpart.c

@@ -21,7 +21,7 @@
  * SPDX-License-Identifier: curl
  *
  ***************************************************************************/
-#include "server_setup.h"
+#include "curl_setup.h"
 
 #include "getpart.h"
 #include <curlx.h> /* from the private lib dir */
@@ -64,7 +64,6 @@ curl_wcsdup_callback Curl_cwcsdup = NULL; /* not use in test code */
 #  pragma warning(pop)
 #endif
 
-
 /*
  * line_length()
  *
@@ -109,7 +108,6 @@ static size_t line_length(const char *buffer, int bytestocheck)
  *   GPE_END_OF_FILE
  *   GPE_OK
  */
-
 static int readline(char **buffer, size_t *bufsize, size_t *length,
                     FILE *stream)
 {
@@ -174,7 +172,6 @@ static int readline(char **buffer, size_t *bufsize, size_t *length,
  *   GPE_OUT_OF_MEMORY
  *   GPE_OK
  */
-
 static int appenddata(char  **dst_buf,   /* dest buffer */
                       size_t *dst_len,   /* dest buffer data length */
                       size_t *dst_alloc, /* dest buffer allocated size */
@@ -274,7 +271,6 @@ static int decodedata(char  **buf,   /* dest buffer */
  *   GPE_OUT_OF_MEMORY
  *   GPE_OK
  */
-
 int getpart(char **outbuf, size_t *outlen,
             const char *main, const char *sub, FILE *stream)
 {