[llvm] [AArch64][GlobalISel] Vector Constant Materialization (PR #67149)

[Amara Emerson via llvm-commits]

https://github.com/aemerson approved this pull request.

Thanks, LGTM. I ran the CTMark suite at -Os and found these improvements:
```
Program                                       size.__TEXT,__text
                                              outputf8k03nj5     outputncrrixth diff
kimwitu++/kc                                  450660.00          450660.00       0.0%
SPASS/SPASS                                   410592.00          410588.00      -0.0%
mafft/pairlocalalign                          243700.00          243680.00      -0.0%
sqlite3/sqlite3                               287312.00          287288.00      -0.0%
consumer-typeset/consumer-typeset             412128.00          412084.00      -0.0%
tramp3d-v4/tramp3d-v4                         364108.00          364064.00      -0.0%
Bullet/bullet                                 450772.00          450688.00      -0.0%
lencod/lencod                                 427716.00          427620.00      -0.0%
ClamAV/clamscan                               381428.00          381340.00      -0.0%
7zip/7zip-benchmark                           566508.00          566236.00      -0.0%
                           Geomean difference                                   -0.0%
```

https://github.com/llvm/llvm-project/pull/67149