[PATTERNS_VIEW] Allow to save combinations as the separate items in a patterns view

[svlad-90]

The idea is that for a specific domain we need to check different use-cases, which are quite complex. They consist of different parts. Some parts are common between those use-cases. The idea is to create the vocabulary of regex patterns for small steps and re-use them between the scenarios.

The issue is that currently, the plugin allows saving only one set of favorite items. But we have around 10 use-cases each of which consists of ~10-20 smaller steps.

To step over this issue we would like to have a possibility to save patterns that do consist of references to the other patterns. There is no need to mix textual regex-es with the references inside one stored element. We are thinking of allowing the user to set the type of the stored element and for "reference-based" elements allow to select the items from the tree.

• It should be possible to include "reference-based items" inside the other "reference-based items".
• We should check that created references are acyclic to avoid recursion.
• In case if some of the referenced items were deleted - they should be removed from the referenced elements
• In case if a type of the element was changed from "referenced-based" to "textual" the default text value should be formed from all referenced values

[svlad-90]

The way to implement:

• Reuse patterns view with limited functionality. Achievable via the initialization switch which can be passed in the constructor of the view and model
• Extension of the persistency to store extended description of the patterns: +pattern-type +pattern-reference-UUID
• Extension of logic to form regex-section
• Handling of corner cases - renaming of the items, removal of items, cyclic references, reference to self etc.