Fixed serialization of composite Ids when setting outputNewIdFormat: false

[tobias-tengler]

Recently I introduced the ability to incrementally adopt the new Id format: a5c1cb1

Underneath it was using the LegacyNodeIdSerializer to write Ids in the old format, as long as the outputNewIdFormat option was set to false.
The LegacyNodeIdSerializer doesn't know about custom INodeValueSerializers though, so you'd end up with a .ToString()ed version of your Id, instead of the value being transformed by your serializer.

This PR changes the behavior of the outputNewIdFormat flag, by still using the serializer infrastructure of the new Id format, but outputting the formatted Id with the delimiters of the legacy format.

I've also increased the test coverage for the various format / parse cases.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.79%. Comparing base (830a96f) to head (e06b78c).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7426      +/-   ##
==========================================
- Coverage   78.85%   77.79%   -1.06%     
==========================================
  Files        2445     2818     +373     
  Lines      120325   141261   +20936     
==========================================
+ Hits        94887   109901   +15014     
- Misses      25438    31360    +5922     

Flag	Coverage Δ
unittests	77.79% <100.00%> (-1.06%)	⬇️

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