Fluentd formatter: format as dictionnary for Record Accessor support

[sbocahu]

Fluentbit, a lightweight Fluentd shipper, only supports dictionnary records for its record accessor functionnality ( https://docs.fluentbit.io/manual/administration/configuring-fluent-bit/record-accessor ) Using keys instead of array indexes is generally easier and less error-prone in any case. This PR changes the Fluentd formatting to return a dictionnary instead of an array.

[Seldaek]

Two issues I have here:

• The tests are broken
• This may not be backwards compatible? I am not knowledgeable enough about Fluentd to say if this would cause issues for existing setups?

[selcukcukur]

@Seldaek Test file corruption is normal. This requires new controls and is unnecessary, there is no situation that will cause an error right now. I think this withdrawal request should not be sent.