Generalize the feature transform to use vec_t macros

This commit generalizes the feature transform to use vec_t macros
that are architecture defined instead of using a seperate code path for each one.

It should make some old architectures (MMX, including improvements by Fanael) faster
and make further such improvements easier in the future.

Includes some corrections to CI for mingw.

closes https://github.com/official-stockfish/Stockfish/pull/3955
closes https://github.com/official-stockfish/Stockfish/pull/3928

No functional change

.github/workflows/stockfish.yml

@@ -82,20 +82,20 @@ jobs:
               name: "Windows 2022 Mingw-w64 GCC x86_64",
               os: windows-2022,
               compiler: g++,
-              comp: gcc,
+              comp: mingw,
               run_64bit_tests: true,
               msys_sys: 'mingw64',
-              msys_env: 'x86_64',
+              msys_env: 'x86_64-gcc',
               shell: 'msys2 {0}'
             }
           - {
               name: "Windows 2022 Mingw-w64 GCC i686",
               os: windows-2022,
               compiler: g++,
-              comp: gcc,
+              comp: mingw,
               run_32bit_tests: true,
               msys_sys: 'mingw32',
-              msys_env: 'i686',
+              msys_env: 'i686-gcc',
               shell: 'msys2 {0}'
             }
           - {
@@ -105,7 +105,7 @@ jobs:
               comp: clang,
               run_64bit_tests: true,
               msys_sys: 'clang64',
-              msys_env: 'clang-x86_64',
+              msys_env: 'clang-x86_64-clang',
               shell: 'msys2 {0}'
             }
 
@@ -129,7 +129,7 @@ jobs:
         uses: msys2/setup-msys2@v2
         with:
           msystem: ${{matrix.config.msys_sys}}
-          install: mingw-w64-${{matrix.config.msys_env}}-${{matrix.config.comp}} make git expect
+          install: mingw-w64-${{matrix.config.msys_env}} make git expect
 
       - name: Download the used network from the fishtest framework
         run: |