Introduce SshSupport to centralize SSH related utility code
As discussed with Thomas here:
https://git.eclipse.org/r/#/c/83506/31/org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/SmudgeFilter.java@349
Move the code from ConfigureGerritAfterCloneTask to SshSupport and
eliminate the slightly modified copy of the code from
LfsConnectionFactory. Separate EGit commit will eliminate the code from
ConfigureGerritAfterCloneTask.
Change-Id: Ifb5adb1342e0fc1f2a70cddf693408d4e0ef7906 Signed-off-by: Markus Duft <markus.duft@ssi-schaefer.com>