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

.github/workflows/macos.yml

@@ -236,7 +236,7 @@ jobs:
               [ "${_chkprefill}" = '_chkprefill' ] && options+=' -D_CURL_PREFILL=OFF'
               cmake -B "bld${_chkprefill}" -G Ninja -D_CURL_PREFILL=ON \
                 -DCMAKE_INSTALL_PREFIX="$HOME"/curl-install \
-                -DCMAKE_UNITY_BUILD=ON -DCURL_TEST_BUNDLES=ON -DCURL_WERROR=ON \
+                -DCMAKE_UNITY_BUILD=ON -DCURL_WERROR=ON \
                 -DCMAKE_OSX_SYSROOT="${sysroot}" \
                 -DCMAKE_C_COMPILER_TARGET="$(uname -m | sed 's/arm64/aarch64/')-apple-darwin$(uname -r)" \
                 ${MATRIX_GENERATE} ${options}
@@ -256,7 +256,7 @@ jobs:
             fi
             [ -n "${MATRIX_MACOS_VERSION_MIN}" ] && CFLAGS+=" -mmacosx-version-min=${MATRIX_MACOS_VERSION_MIN}"
             [[ "${MATRIX_INSTALL_STEPS}" = *'pytest'* ]] && options+=' --with-test-vsftpd=no'  # Skip ~20 tests that stretch run time by 7x on macOS
-            mkdir bld && cd bld && ../configure --enable-unity --enable-test-bundles --enable-warnings --enable-werror \
+            mkdir bld && cd bld && ../configure --enable-unity --enable-warnings --enable-werror \
               --disable-dependency-tracking \
               --with-libpsl=/opt/homebrew/opt/libpsl \
               ${MATRIX_CONFIGURE} ${options}
@@ -458,7 +458,7 @@ jobs:
             [ -n "${MATRIX_MACOS_VERSION_MIN}" ] && options+=" -DCMAKE_OSX_DEPLOYMENT_TARGET=${MATRIX_MACOS_VERSION_MIN}"
             # would pick up nghttp2, libidn2, and libssh2
             cmake -B bld -G Ninja -D_CURL_PREFILL=ON \
-              -DCMAKE_UNITY_BUILD=ON -DCURL_TEST_BUNDLES=ON -DCURL_WERROR=ON \
+              -DCMAKE_UNITY_BUILD=ON -DCURL_WERROR=ON \
               -DCMAKE_OSX_SYSROOT="${sysroot}" \
               -DCMAKE_C_COMPILER_TARGET="$(uname -m | sed 's/arm64/aarch64/')-apple-darwin$(uname -r)" \
               -DCMAKE_IGNORE_PREFIX_PATH="$(brew --prefix)" \
@@ -478,7 +478,7 @@ jobs:
             fi
             [ -n "${MATRIX_MACOS_VERSION_MIN}" ] && CFLAGS+=" -mmacosx-version-min=${MATRIX_MACOS_VERSION_MIN}"
             # would pick up nghttp2, libidn2, but libssh2 is disabled by default
-            mkdir bld && cd bld && ../configure --enable-unity --enable-test-bundles --enable-warnings --enable-werror \
+            mkdir bld && cd bld && ../configure --enable-unity --enable-warnings --enable-werror \
               --disable-dependency-tracking \
               --disable-docs --disable-manual \
               --with-openssl="$(brew --prefix openssl)" \