Fix so that term hierarchy with multiple levels is sorted correctly

[patrikhellgren]

Q	A
Bug fix?	[X]
New feature?	[ ]
New sample?	[ ]
Related issues?

What's in this Pull Request?

Fix so that term hierarchy with multiple levels is sorted correctly, both by name and by custom sort order.
If you before this fix had the following Term Set defined it would not have been displayed correctly in the picker pane:

TestTermSet
  |
  |----1
  |    |
  |    |--1a
  |    |--1b
  |
  |----10
  |    |
  |    |--10a
  |    |--10b
  |
  |----100
  |    |
  |    |--100a
  |    |--100b

[msftclas]

All CLA requirements met.

[codecov-io]

Codecov Report

Merging #217 into dev will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##              dev     #217   +/-   ##
=======================================
  Coverage   72.71%   72.71%           
=======================================
  Files          16       16           
  Lines         744      744           
  Branches      138      148   +10     
=======================================
  Hits          541      541           
  Misses        159      159           
  Partials       44       44

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[patrikhellgren]

If this contribution will be visible among the monthly contributors to PnP, please also include the logo and name of my company. You will find the logo here: https://github.com/SherpasGroup

[estruyf]

edit: we might have to do a rewrite of this implementation, as the sort logic got changed a bit to fix issue #229.

[estruyf]

Just manually implemented the fix into the service as there were some conflicts. Of what I've seen is that there is only one change required, and that is related to IsRoot check and CustomSortOrderIndex. As the sort logic was changed, don't think we have to implement or do any changes to that anymore.

Feel free to verify the latest beta. I also created an issue for this to track this: #231

[estruyf]

Closing this PR as it was manually merged.