[JENKINS-20609] refactored script hook

in preparation of introducing other hooks
doc improvements
Fix javadoc warning in Combination

Removed import that was only used to attempt to satisfy the javadoc
reference to the class.

Replaced the javadoc reference to an inner class with a fully
qualified reference to the same inner class.
recover from exception
defining hooks  for customizing variable bindings
[FIXED JENKINS-20609]

Implemented the hook
expose additional variables
[FIXED JENKINS-20615] - Fixed variable reference in TestResult/index_ru.properties
Resolves https://issues.jenkins-ci.org/browse/JENKINS-20615

Signed-off-by: Oleg Nenashev <nenashev@synopsys.com>
[JENKINS-20609] test case
Merge pull request #1021 from synopsys-arc-oss/russian-localization-fix

[FIXED JENKINS-20615] - Fixed variable reference in TestResult/index_ru....
Merge pull request #1020 from MarkEWaite/javadoc-fixes-j

Fix javadoc warning in Combination