FRR: T4020: Updated CLI options processing for FRR daemons

Instead of analyzing options for each daemon now we use a single
template for the whole configuration file. This makes logic a bit less
flexible, but much easier.
Removed unnecessary check for returned by the
conf.get_config_dict(base) config.

Also, added the ability to disable strip() of file content while
using read_file() what is necessary for proper comparing with
updated content.