Add LoongArch64 support

[Chris-wh233]

This PR adds basic support for LoongArch64. The minimum target CPU is a LoongArch64 CPU that supports LSX.

Native build and testing have passed.

• Debian forky

• GCC/G++ 14

• Conan 2.28.1

• CPU with LSX and LASX

Cross-build validation

A separate GitHub Actions workflow successfully completed:

• GCC 14 LoongArch64 cross-build

• Sparse codec source smoke tests

• Full Knowhere build and selected unit tests

Workflow run:

https://github.com/Chris-wh233/knowhere/actions/runs/34106005065

Corresponding commit:

Chris-wh233@cbaeffe

[sre-ci-robot]

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[sre-ci-robot]

Welcome @Chris-wh233! It looks like this is your first PR to zilliztech/knowhere 🎉

[mergify]

@Chris-wh233 🔍 Important: PR Classification Needed!

For efficient project management and a seamless review process, it's essential to classify your PR correctly. Here's how:

1. If you're fixing a bug, label it as kind/bug.
2. For small tweaks (less than 20 lines without altering any functionality), please use kind/improvement.
3. Significant changes that don't modify existing functionalities should be tagged as kind/enhancement.
4. Adjusting APIs or changing functionality? Go with kind/feature.

For any PR outside the kind/improvement category, ensure you link to the associated issue using the format: “issue: #”.

Thanks for your efforts and contribution to the community!.

[Chris-wh233]

/kind improvement

[alexanderguzhva]

@Chris-wh233 Thanks for the contribution, we're taking a look. You may also wish to add the code to the Faiss (https://github.com/facebookresearch/faiss) baseline that this library depends on.