Import is too slow

[ulcuber]

• Optimize BaseContext variableToArray #520
• Optional check template name in use #521
• Mass delete templates in container version #522
• deleteContainer* (Template) methods every time check template references causing loop in loop but EVERY template will be deleted so checking references makes no sense
• getContainer* models methods causes enrich* methods while only id* used. Better use dao
• the best for deletion would be mass deletion to prevent n+1 queries
• providers methods get(Tag|Trigger|Variable), checkIsValid* use loops to find template. See Import: optimize validation loops to dictionary #532
• accessValidator->checkUseCustomTemplatesCapability applied only to idSite but not for each template so it could be cached for loops
• Request::processRequest causes too much duplicate and unnecessary logic such as accessValidator->checkWriteCapability, containers->checkContainerExists, accessValidator->checkUseCustomTemplatesCapability that already checked in parent controller and sanitizing-unsanitizing parameters. Maybe better use models as they contain necessary validation. Optimize import: use models instead of emulating requests in loop #533
• Comparison getSupportedComparisons output never changes therefore should be cached as it causes 24*n translations. checkIsValidComparison could also use dictionary (array) instead of loop
• it would be useful to have validateValues, formatParameters methods in models to be public to bypass duplicate *Provider->checkIsValid*
• TriggerIds validator could check all triggers once to prevent n+1 queries
• Since import uses clean version duplicate template names should be checked in Import loop using dictionary (array) to prevent all isNameInUse unnecessary queries
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