Add option to merge via ruby objects

[jrperron88-zz]

Currently we are using string replace to preserve formatting and comments.

Add an option to the command to support using object to object merging and output.

The merge functionality already exists in the codebase.

The to_ruby function will need to be tweaked for formatting

--merge will use object merging

--sub will use current string substitution

inspec_delta profile update --profile_path --stig_file_path <stig.xml> (–-merge) (--sub)