feat: add --images support to unstructured-get-json.sh (#3888)

E.g., now can run:
```bash
# extracts base64 encoded image data for `Table` and `Image` elements
$ unstructured-get-json.sh --trace --verbose --images /t/docs/Captur-1317-5_ENG-p5.pdf

# also extracts `Title` elements (see screenshot)
$ IMAGE_BLOCK_TYPES='"title","table","image"' unstructured-get-json.sh --trace --verbose --images /t/docs/Captur-1317-5_ENG-p5.pdf
```

It was discovered during testing that "narrativetext" does not work,
probably due to camel casing of NarrativeText 😬

![image](https://github.com/user-attachments/assets/e6414a57-81e1-4560-b1b2-dce3b1c2c804)

scripts/user/unstructured-get-json.sh

@@ -17,6 +17,7 @@ Options:
   --fast          fast strategy: No OCR, just extract embedded text
   --ocr-only      ocr_only strategy: Perform OCR (Optical Character Recognition) only. No layout segmentation.
   --tables        Enable table extraction: tables are represented as html in metadata
+  --images        Include base64images in json
   --coordinates   Include coordinates in the output
   --trace         Enable trace logging for debugging, useful to cut and paste the executed curl call
   --verbose       Enable verbose logging including printing first 8 elements to stdout
@@ -39,6 +40,7 @@ if [ "$#" -eq 0 ]; then
   exit 1
 fi
 
+IMAGE_BLOCK_TYPES=${IMAGE_BLOCK_TYPES:-'"image", "table"'}
 API_KEY=${UNST_API_KEY:-""}
 TMP_DOWNLOADS_DIR="$HOME/tmp/unst-downloads"
 TMP_OUTPUTS_DIR="$HOME/tmp/unst-outputs"
@@ -68,6 +70,7 @@ TRACE=false
 COORDINATES=false
 FREEMIUM=false
 TABLES=true
+IMAGES=false
 S3=""
 
 while [[ "$#" -gt 0 ]]; do
@@ -100,6 +103,10 @@ while [[ "$#" -gt 0 ]]; do
     TABLES=true
     shift
     ;;
+  --images)
+    IMAGES=true
+    shift
+    ;;
   --coordinates)
     COORDINATES=true
     shift
@@ -180,12 +187,14 @@ CURL_COORDINATES=()
 [[ "$COORDINATES" == "true" ]] && CURL_COORDINATES=(-F "coordinates=true")
 CURL_TABLES=()
 [[ "$TABLES" == "true" ]] && CURL_TABLES=(-F "skip_infer_table_types='[]'")
+CURL_IMAGES=()
+[[ "$IMAGES" == "true" ]] && CURL_IMAGES=(-F "extract_image_block_types=[$IMAGE_BLOCK_TYPES]")
 
 curl -q -X 'POST' \
   "$API_ENDPOINT" \
   "${CURL_API_KEY[@]}" -H 'accept: application/json' \
   -H 'Content-Type: multipart/form-data' \
-  "${CURL_STRATEGY[@]}" "${CURL_COORDINATES[@]}" "${CURL_TABLES[@]}" -F "files=@${INPUT_FILEPATH}" \
+  "${CURL_STRATEGY[@]}" "${CURL_COORDINATES[@]}" "${CURL_TABLES[@]}" "${CURL_IMAGES[@]}" -F "files=@${INPUT_FILEPATH}" \
   -o "${JSON_OUTPUT_FILEPATH}"
 
 JSON_FILE_SIZE=$(wc -c <"${JSON_OUTPUT_FILEPATH}")