GUACAMOLE-2139: Migrate all license information to new automated format.

doc/licenses/error-prone/LICENSE

@@ -0,0 +1,4 @@
+# Name:    Error Prone
+# URL:     https://errorprone.info/
+# From:    'Google Inc.' (http://www.google.com/)
+# License: Apache v2.0

doc/licenses/error-prone/dep-coordinates.txt

@@ -0,0 +1 @@
+com.google.errorprone:error_prone_annotations:jar:*