doc mapper parse error on `otel_logs_v0_7`

Describe the bug

According to the log data spec, body field should support any type of data.

The doc mapping of the field is specified as json, but it seems to only accept JSON objects, not JSON arrays.

quickwit-1        | 2024-08-26T08:20:37.205Z  WARN quickwit_indexing::actors::doc_processor: doc mapper parse error: the document contains an array of values but a single value is expected: "body" index_id="otel-logs-v0_7" source_id="_ingest-api-source"

So log records generated by OTEL's official SDK are not indexed properly.

I used logtape, which add body field as array.

Steps to reproduce (if applicable)

Full setup: https://github.com/cometkim/quickwit-tutorial

Expected behavior

Valid OTEL logs must be able to be indexed.

Maybe by supporting more JSON values, or by changing the field type dynamic.

Configuration:

1. Output of quickwit --version: 0.8.2
2. The index_config.yaml: The built-in otel_logs_v0_7