This update allows clickhouse-destination to support multiple JSON structures for ClickHouse ingestion.

• Supports the existing JSONEachRow format (default).
• Adds a new JSONCompactEachRow format, which is more compact but less human-readable.
• Invalid configuration values are rejected with an error, e.g.:
  Error parsing within destination: invalid format value 'invalid-format', possible values: [JSONEachRow, JSONCompactEachRow].

example:

destination {
  clickhouse (
    ...
    json-var(json("$my_filterx_json_var"))
    format("JSONCompactEachRow")
    ...
  );
};

JSONEachRow (each JSON object per line, more readable):

{"id":1,"name":"foo","value":42}
{"id":2,"name":"bar","value":17}

JSONCompactEachRow (compact array-based row representation):

[1,"foo",42]
[2,"bar",17]