Add option to embed json fields metadata inside the log payload

[rishiyemme]

Adding a boolean option moveFieldsIntoPayload to inject specified fields into the log JSON payload to allow for dynamic auto JSON parsing in Sumo. Enabling this option would also prevent fields from being sent in the HTTP request to Sumo.

[vsinghal13]

LGTM.
We need to explicitly call out in the release notes that enabling this feature may be a breaking change if people have existing searches/dashboards set up based on json fields.

[rishiyemme]

Pushed some changes while waiting for some customer feedback on the log format when moveFieldsIntoPayload = true.
Per the latest changes, whenever moveFieldsIntoPayload is true, we always format the log payload into a JSON log format looking like

{"timestamp":1664396202215,"log":"{"timestamp":1654016401446,"PID":"3","USER":"root","MEM":"0.0","CPU":"0.0"}","metadata":{"bigintfield":"228930314431312345","boolfield":"true","intfield":"100","stringfield":"stringvalue"}}

essentially ignoring the payloadText field. The metadata field will include all fields.

Otherwise when moveFieldsIntoPayload is false, we revert to the previous behavior.

[vsinghal13]

Otherwise when moveFieldsIntoPayload is true, we revert to the previous behavior.
@rishiyemme you meant when it is set to false, we revert to previous behavior.

[vsinghal13]

what is the different between this file and the test-fields-in-payload-payloadText file?

Probably the other one is missing payloadWrapperKey?