[Sequester] Add tag based on labels on issues

[BillWagner]

Sequester should be able to add Azure DevOps tags based on issue labels. The first use case is to add the "new-feature" tag in AzDo for any issues that represent new features.

The config file should add an array of configured label / tag pairs. When importing an issue, the System.Tags field should be set to any tags where matching labels are found.

When updating an issue, tags should not be removed, but any new tags found should be added.

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Associated WorkItem - 233471