sb: Align the version processing with rtems-tools.

- Use the same VERSION file format as rtems-tools so a common release
  generation can be used.

- The version.py is almost the same as rtems-tools. There are some
  minor differences, one is the RTEMS version is present in this
  file while rtems-tool uses config/rtems-release.ini.

Updates #3822

source-builder/sb/build.py

@@ -672,7 +672,7 @@ def run(args):
     try:
         optargs = { '--list-configs': 'List available configurations' }
         opts = options.load(args, optargs)
-        log.notice('RTEMS Source Builder, Package Builder, %s' % (version.str()))
+        log.notice('RTEMS Source Builder, Package Builder, %s' % (version.string()))
         opts.log_info()
         if not check.host_setup(opts):
             if not opts.force():