GUACAMOLE-1594: Update all Java and JavaScript dependencies to latest compatible.

NOTE: Several WebPack plugins could not be updated as all plugins within
WebPack's "webpack-contrib" have dropped support for WebPack v4
entirely, but Closure Compiler only supports WebPack v4.

doc/licenses/kotlin-1.7.20/NOTICE.txt

@@ -0,0 +1,2 @@
+Kotlin Compiler
+Copyright 2010-2020 JetBrains s.r.o and respective authors and developers

doc/licenses/kotlin-1.7.20/README

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+Kotlin (https://kotlinlang.org/)
+--------------------------------
+
+    Version: 1.7.20
+    From: 'JetBrains s.r.o and respective authors and developers'
+    License(s):
+        Apache v2.0
+

doc/licenses/kotlin-1.7.20/dep-coordinates.txt

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+org.jetbrains.kotlin:kotlin-reflect:jar:1.7.20
+org.jetbrains.kotlin:kotlin-stdlib:jar:1.7.20
+org.jetbrains.kotlin:kotlin-stdlib-common:jar:1.7.20
+org.jetbrains.kotlin:kotlin-stdlib-jdk8:jar:1.7.20
+org.jetbrains.kotlin:kotlin-stdlib-jdk7:jar:1.7.20