[PORT] Update IMemory interface and tryEvaluate for expression

[cosmicshuai]

fixes: #1966

Add an optional parameter options in tryEvaluate.

Inside options, we allows user to set a callback function which been called whenever there is a null found in memory path, except for those in boolean context.

[coveralls]

Pull Request Test Coverage Report for Build 116818

• 90 of 96 (93.75%) changed or added relevant lines in 5 files are covered.
• 9 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.05%) to 81.398%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
libraries/adaptive-expressions/src/expressionFunctions.ts	83	89	93.26%

Files with Coverage Reduction	New Missed Lines	%
libraries/botframework-streaming/src/webSocket/webSocketTransport.ts	2	80.65%
libraries/botframework-streaming/src/webSocket/webSocketServer.ts	7	66.67%

Totals
Change from base Build 116308:	-0.05%
Covered Lines:	9327
Relevant Lines:	11033

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💛 - Coveralls