[Bug fix] Update Import model while importing assessment

[stuti149]

Bug: When assessment is imported first time it imports correct. When another assessment is imported after it, the previously imported assessment is shown again and not the new one.

Fix: Model to new imported assessment was not updated.

[coveralls]

Pull Request Test Coverage Report for Build 6925871178

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.001%) to 41.568%

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Files with Coverage Reduction	New Missed Lines	%
src/sql/workbench/services/connection/browser/connectionDialogWidget.ts	1	73.44%

Totals
Change from base Build 6908827043:	-0.001%
Covered Lines:	30790
Relevant Lines:	69372

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💛 - Coveralls