ximprovement: Add toString UserConfiguration #14273

Job	Run time
Gradle MacOS integration	11m 32s
windows-latest jdk-17 unit tests 1 / 2	33m 3s
Sbt integration	51m 42s
windows-latest jdk-17 unit tests 2 / 2	2m 14s
Maven integration	11m 22s
macOS-latest jdk-17 unit tests 1 / 2	54m 5s
Gradle integration	12m 20s
macOS-latest jdk-17 unit tests 2 / 2	43m 35s
Scala CLI integration	16m 17s
ubuntu-latest jdk-17 unit tests 1 / 2	17m 58s
Mill integration	40m 33s
ubuntu-latest jdk-17 unit tests 2 / 2	16m 14s
Bazel integration	13m 16s
LSP integration tests	35m 15s
Scala cross tests	33m 44s
Formatting	45s
Scalafix and docs	4m 57s
Sbt-metals/scripted jdk11	2m 39s
Scala javapc tests	1m 47s
Scala 2.11 cross tests	4m 14s
MiMa	53s
	6h 48m 25s

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