OPENDJ-1714: Code cleanup

* Installer.java
** Formats code
** Splits createData(..) and configureServer(..) method
** Extracts methods configureCertificate(SecurityOptions), configureKeyAndTrustStore(...), configureTrustStore(...)
** Creates static final String for the userRoot backendName
** Removes getBackendName() method
** Reorganizes static and instance attribute declarations

* InstallDS.java
** Formats code

* NewSuffixOptions.java
** Add a method to convert enum local type to InstallprogressStep

* SetupUtils.java
** Merged method exportCertificate(CertificateManager, String) with exportCertificate(CertificateManager, String, String)