Add ssh utility as before to allow ssh usage of git

Also as before, add less utility to better git diff output
related to eclipse-che/che#12850

Change-Id: I1d1b7b83f02f5ebfc9957f3d5106c1ce13a080a6
Signed-off-by: Florent Benoit <fbenoit@redhat.com>

dockerfiles/theia/Dockerfile

@@ -110,7 +110,9 @@ COPY --from=builder /home/theia-dev/theia-source-code/production/plugins /defaul
 # Install bzip2 to unpack files
 # Install which tool in order to search git
 # Install curl and bash
-RUN apk add --update --no-cache sudo git bzip2 which bash curl
+# Install ssh for cloning ssh-repositories
+# Install less for handling git diff properly
+RUN apk add --update --no-cache sudo git bzip2 which bash curl openssh openssh-keygen less
 RUN adduser -D -S -u 1001 -G root -h ${HOME} -s /bin/sh theia \
     && echo "%wheel ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers \
     # Create /projects for Che