migration: Move migrate_use_tls() to options.c

Once there, rename it to migrate_tls() and make it return bool for
consistency.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

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Fix typos found by fabiano
5 files changed