feat(new encoding): add pretty json encoding (#20384)

* feat(new encoding): add pretty json encoding

* chore(lint): fix cargo fmt lints

* feat(new codec): update default console logger to use pretty json

* docs(new codec): update docs for pretty json

* chore(changelog): add changelog.d entry

* fix(tests): update tests for pretty_json codec

* refactor(pretty_json): adds a field to existing json codec instead of a new pretty_json codec

* refactor(codecs): rename pretty field name for json codec

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Co-authored-by: Jesse Szwedko <jesse.szwedko@datadoghq.com>