[v1.14] Add composite embedders and pooling for huggingface embedders (experimental)

This issue follows the changes related to Meilisearch v1.14.0 mega issue.

Description

Update embedders API to be compatible with Meilisearch v1.14.0

For more context, see the related issue in Meilisearch: https://github.com/meilisearch/meilisearch/issues/5343

Tasks

• [ ] Add new pooling parameter for huggingFace embedders
• [ ] Add new composite source for embedders

For reference, here's how this works using Meilisearch JS SDK:

client
  .index('index_name')
  .updateEmbedders({
    embedder_name: {
      source: "composite",
      searchEmbedder: {
        source: "huggingFace",
        model:
          "sentence-transformers/paraphrase-multilingual-MiniLM-L12-v2",
        pooling: "useModel",
      },
      indexingEmbedder: {
        source: "huggingFace",
        model:
          "sentence-transformers/paraphrase-multilingual-MiniLM-L12-v2",
        documentTemplate: "{{doc.title}}",
        pooling: "useModel",
        documentTemplateMaxBytes: 500,
      },
    },
  });