Move generated code template to file

In preparation of enhancing the generated code format, the template used
has been externalized and will continue to be modified in future commits
to parse & generate more efficiently.

Tested:
    Generated code remains unchanged

Resolves openbmc/phosphor-fan-presence#8

Change-Id: Ifbf718e8a22acb2f2f939bbdcc2e7fe041e9ed58
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
3 files changed