This PR is related to #75 issue
This PR is result of global work on List 2.0

Problems

• Could not use List or Checklist data format for Nested List
• Can not use cheklist as style of the nested list
• Data model has no place for meta (e. g. checked field for checklist)
• Nesting is not customizable
• Can not start ordered list with custom variable
• Can not change counters for ordered list
• Can not split list on enter in the empty item in the midle of the list
• Does not support backspace on the start of the first item
• Nesting works unexpected sometimes
• One file architecture
• Shortcut fails to make defaultStyle effective
• defaultStyle is not respected by toolbox

Solutions

• Implement checklist as style of the nested list
• Support new data model with meta attribute for each item:

interface ListItem {
  content: string;

  meta: OrderedListMeta | UnorderedListMeta | ChecklistMeta;      // meta should depend on list type
  
  items: ListItem[];
}

• Separate List rendering and tabulation (rendered should render items and wrappers dependant on list style), tabulator should handle keydowns and work with editor events
• Rerender list, when style changed
• Export all list styles to toolbox
• Implement data converter from old List and Checklist formats to new Nested List
• Support nesting customisation by maxLevel config option
• Support <ol> attributes, in config (such as type, start)

Status

• Separate rendering and tabulation
• Support checklist for Nested checklist support #11
• List rerendering on style change
• Support new data model
• Add nesting customisation for Max level depth implementation #80
• Add ordered list customisation for [Feature Request] start ordered list by a different number #66
• Refactor keydown behaviour
• • Backspace at beginning of first list item for Backspace at beginning of first list item #27, [Bug] Can not delete first item #43
• • Backspace in empty list item for Delete in empty list item #28
• • Split list on enter in emtpy item for Split list on enter in empty item #30
• • Merge parapraph with list on backspace in parapraph for Turning paragraph into list item by hitting backspace at the beginning #32
• Export all list styles into toolbox for Tools Icon #70
• Support Checklist and List data models for [Question] How to upgrade from List to this Nested List plugin? #87, Make it compatible with @editorjs/list #15

resolves #11
resolves #15
resolves #27
resolves #28
resolves #30
resolves #32
resolves #43
resolves #66
resolves #70
resolves #75
resolves #80
resolves #87