Fix CreateSamplingHandler to use ChatRole.Tool for tool result messages #1562

Job	Run time
build (macos-latest, Release)	5m 57s
build (ubuntu-latest, Debug)	6m 21s
build (windows-latest, Debug)	8m 7s
build (macos-latest, Debug)	7m 9s
build (ubuntu-latest, Release)	5m 42s
build (windows-latest, Release)	8m 40s
publish-coverage	0s
	41m 56s

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