Refactoring - move job-specific handlers to JobSubstitutionHelper

Signed-off-by: Oleg Nenashev <o.v.nenashev@gmail.com>
[FIXED JENKINS-26119] - Inject custom JOB_NAME during the environment substitution

Signed-off-by: Oleg Nenashev <o.v.nenashev@gmail.com>
Merge pull request #65 from synopsys-arc-oss/JENKINS-26119-fix

[FIXED JENKINS-26119] - Restore the legacy variable escaping approach