fix: removeIED - prevent duplicate LNode's

[stee-re]

resolves #121

Summary

When multiple IEDs reference the same LNode, removing those IEDs sequentially can result in duplicate LNode
entries with iedName="None". This PR modifies the default behaviour for removeIED() to delete all LNodes bound to that IED by default, but exposes a new optional flag preserveLNodes which will instead, set the LNodes ideName="None". In cases where setting the iedName="None" would lead to a duplicate LNode, then it is removed instead.
E.g.

remove(myIEDElement, {preserveLNodes: true});

Changes

• tIED/removeIED.ts:
  • Added RemoveIedOptions interface with an optional preserveLNodes flag (defaults to false)
  • Added the following LNode related functions:
  • removeBoundLNodes() - Default handling for LNodes - find any (public) matching LNodes and create a Remove edit for them.
  • detachLNodeBindings() - if "preserveLNodes flag set, this function is called instead, to instead set the LNodes iedName to "None", taking care to avoid duplicates. Any LNodes encountered which would cause a duplicate, are removed instead.

Helper functions

• lNodeKey - creates a key for the LNode based on all the other attributes (except iedName) which combined, must be unique.
• removeLNode() & setLNodeToNone() - oneliner functions, there only to make the code more readable.
• getLNodeByIedName() used to find the bound LNodes (and the specification LNodes (set ot None))

Other Changed files

• index.ts: Exported RemoveIedOptions type
• tIED/removeIED.spec.ts: Added tests for LNode removal and opt-in LNode updating behaviour
• tIED/removeIED.testfile.ts: Added test fixture with duplicate LNode scenario
• .gitignore: Added IDE and build artifact patterns

Code coverage 99.52%