chore(new sink): add RFC for Google Chronicle sink (#12733)

* Add RFC for Google Chronicle sink

Signed-off-by: Stephen Wakely <fungus.humungus@gmail.com>

* Add section discussing Schema.

Signed-off-by: Stephen Wakely <fungus.humungus@gmail.com>

* Add log_types question.

Signed-off-by: Stephen Wakely <fungus.humungus@gmail.com>

* Separate into multiple sinks.

Signed-off-by: Stephen Wakely <fungus.humungus@gmail.com>

* Added section on retry logic.

Signed-off-by: Stephen Wakely <fungus.humungus@gmail.com>

* Respond to feedback.

Signed-off-by: Stephen Wakely <fungus.humungus@gmail.com>