iec, rec: Abstract out common seba_on_arm usecase

- move seba_on_arm IEC usecase to its own macros/templates files;
- enable seba_on_arm install/test jobs for REC deployments running
  on aarch64 baremetal nodes;
- replace dashes with underscores in jjb variables that need to be
  handled by the jinja2 parser, since jinja2 does not allow dashes
  in variable names;

While at it, add vim temporary files ('*.sw?') to .gitignore.

Change-Id: I62ae4ebfd4955fb484876e3a63c8f02a77e90b38
Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>