Enable fastembed as a local embedding vendor (#12)

* Prepend all Langchain-based embeddings with LC

* Provide vanilla OpenAI embeddings

* Add test for AzureOpenAIEmbeddings and OpenAIEmbeddings

* Incorporate fastembed

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Co-authored-by: ian_Cin <ian@cinnamon.is>

.github/workflows/unit-test.yaml

@@ -100,6 +100,11 @@ jobs:
           path: ${{ env.pythonLocation }}
           key: ${{ steps.restore-dependencies.outputs.cache-primary-key }}
 
+      - name: Install OS-based packages
+        run: |
+          sudo apt update -qqy
+          sudo apt install -y poppler-utils libpoppler-dev tesseract-ocr
+
       - name: Test kotaemon with pytest
         run: |
           pip show pytest