[release/3.0] Fixes NER to correctly expand/shrink the labels

[github-actions[bot]]

Backport of #6928 to release/3.0

/cc @michaelgsharp

Customer Impact

Initially, when a work was split into multiple tokens, the user had to figure that out and expand the labels as well. This PR fixes that by auto expanding/contracting the labels as needed.

Testing

There are automated tests that have examples that were problematic during testing, as well as a complete run was done on a GPU machine (75k lines in the test file).

Risk

With the automated tests and full GPU machine test run, minimal to no risk.

[michaelgsharp]

They can just delete it.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

:exclamation: No coverage uploaded for pull request base (release/3.0@66c06e6). Click here to learn what that means.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## release/3.0 #6946 +/- ## ============================================== Coverage ? 68.80% ============================================== Files ? 1240 Lines ? 249601 Branches ? 25509 ============================================== Hits ? 171745 Misses ? 71256 Partials ? 6600 ``` | [Flag](https://app.codecov.io/gh/dotnet/machinelearning/pull/6946/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | Coverage Δ | | |---|---|---| | [Debug](https://app.codecov.io/gh/dotnet/machinelearning/pull/6946/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | `68.80% <0.00%> (?)` | | | [production](https://app.codecov.io/gh/dotnet/machinelearning/pull/6946/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | `63.27% <0.00%> (?)` | | | [test](https://app.codecov.io/gh/dotnet/machinelearning/pull/6946/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | `88.41% <0.00%> (?)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet#carryforward-flags-in-the-pull-request-comment) to find out more.