New onchanges/onfail failure types for requisite resolver

Refs #16370
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Fix for an exception that was causing the salt minion not to start up properly.
Merge pull request #16613 from cachedout/issue_16370_2

New onchanges/onfail failure types for requisite resolver (try two)
Merge pull request #16625 from garethgreenaway/function_error_broken_minion

Fix to minion.py
Added SaltConf15 banner and links to sidebar