Update playbooks to handle SLES 15

[sej-jackson]

Now that SLES 15 is available, let's get the playbooks updated to handle it.

Will add list of known issues once I've started testing properly, but @Willsparker has already started work on this, so let's have somewhere to track and discuss what we know so far...

[Willsparker]

I feel I should explain the above PR in more depth in here to show whats already been done:

The libelf0 package that couldn't be installed was removed from Build_Tool_Packages, and added to the SLES11 and SLES12 specific package lists.
I added a section for SLES15 specific build packages- I built this list based off SLES12's list and any error messages I got compiling JDK8-J9. Where possible I'd use -devel. I replaced libelf0 with libelf-devel and this seems to suffice.
The only package unavailable was libdwarf-devel however, so I added the repository containing that, into the ../Common/tasks/SLES.yml file.
I also added the same conditionals on Running ./configure & make for expat on Linux x86-64 as there were for the rest of the tasks involving expat.

[Willsparker]

Latest commit on the PR is to add SLES15 to the conditions to start the chronyd service instead of using ntp, and to move ntp to SLES11 and SLES12 specific package lists, as ntp is available on SLES15-SP0, not SLES15-SP1.

[Willsparker]

With the above PR merged, we can include support for SLES15 SP1 too. @sej-jackson was saying that most of the above changes work for SP1, except the package pulseaudio doesn't exist in the default repos. There's also an issue with GIT_Source not build correctly via ansible, however works manually.

[Willsparker]

The above issue with Git_Source was due to the machine not having sudo installed by default. However, I don't think sudo needs to be put into the ./configure and make steps, as the become parameter is set. If this is required, I can add sudo to the package list and make a task that inserts the user into the sudoers file.