add back a function people tend to use in the logging code (#54597)

Apparently, people use this function so let's put it back to reduce
unnecessary breakage. This was moved in
#54428.

Co-authored-by: KristofferC <kristoffer.carlsson@juliacomputing.com>

Author: 2 people

stdlib/Logging/src/Logging.jl

@@ -70,6 +70,9 @@ const AboveMaxLevel = Base.CoreLogging.AboveMaxLevel
 using Base.CoreLogging:
     closed_stream, ConsoleLogger, default_metafmt
 
+# Some packages use `Logging.default_logcolor`
+const default_logcolor = Base.CoreLogging.default_logcolor
+
 export
     AbstractLogger,
     LogLevel,