Fixes #11258 - validation handles blank provider

(cherry picked from commit 3b27c173467c3ab4b53e844913cfd559b78d44ac)

Fixes #10635 - Formalize deprecation warning

(cherry picked from commit 319d1ffbed54f2c9eb988d132ec1586fb4d7c428)

Fixes #10727 - Added validation to require BMC Smart proxy in order to add BMC nic

Fixes #10713 - improved backtrace logging

• full trace in 500 page in production shows really the full trace
• Foreman::Logging.exception as an unified entry point for exceptions logging
• the backtrace cleaner doesn't delete the plugins
• the orchestration exceptions gets the backtrace covered by logger...

Fixes #7096 - Adds STI to templates

This commit converts Ptables to be just another type of Template so it
gets the same features as ConfigTemplate. ConfigTemplate was renamed to
ProvisioningTemplate to reflect UI and the name under it's commonly known.

Fixes #10566 - allow identifier modifications that do not change interface type

fixes #10646 - disable NIC subnet taxonomy checks when feature's disabled

Refs #6518 - Use #find instead of #select #first to choose a BMC proxy for the subnet

Enumerable#find more idiomatic in Ruby, and since it stops at the first match it
may be marginally faster.

Fixes #10442 - dry up host managed logic

Fixes #10307 - editing host with 'unattended: false' no longer results in error