Declare depth in formatter conf types for dialyzer

`translate_generic_conf/2` returns a map carrying a `depth` key, which
the plaintext and JSON formatter translators merge into their results.
The `formatter_plaintext_conf()` and `formatter_json_conf()` types do not
declare `depth`, so dialyzer infers a return that violates the
`translate_*_formatter_conf` contracts and reports "has no local return".

Add `depth := unlimited | pos_integer()` to both types, matching the
field already present on `formatter_generic_conf()`.

Author: lukebakken

deps/rabbitmq_prelaunch/src/rabbit_prelaunch_early_logging.erl

@@ -285,6 +285,7 @@ translate_generic_conf(Var, Conf) ->
 -type formatter_plaintext_conf() :: #{time_format := time_format(),
                                       level_format := level_format(),
                                       single_line := boolean(),
+                                      depth := unlimited | pos_integer(),
                                       prefix_format := line_format(),
                                       line_format := line_format(),
                                       use_colors := boolean(),
@@ -414,6 +415,7 @@ translate_colors_conf(_, _) ->
 -type formatter_json_conf() :: #{time_format := time_format(),
                                  level_format := level_format(),
                                  single_line := boolean(),
+                                 depth := unlimited | pos_integer(),
                                  field_map := json_field_map(),
                                  verbosity_map := json_verbosity_map()}.