fix: [#3969] useLanguagePolicy setting turn state, instead of languag…

[joshgummersall]

…ePolicy (#3972)

• Revert "Revert "port: Register missingProperties custom function to get all variables the template contains (port: Register missingProperties custom function to get all variables the template contains #3885)" (fix: Revert: "port: Register missingProperties custom function to get all variables the template contains" #3970)"

This reverts commit 619ac13.

• fix: useLanguagePolicy setting turn state, instead of languagePolicy

#minor

[coveralls]

Pull Request Test Coverage Report for Build 1427012044

• 69 of 78 (88.46%) changed or added relevant lines in 8 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.05%) to 84.59%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
libraries/botbuilder-dialogs-adaptive/src/functions/missingPropertiesFunction.ts	12	14	85.71%
libraries/botbuilder-dialogs-adaptive/src/generators/multiLanguageGeneratorBase.ts	40	47	85.11%

Totals
Change from base Build 1422089706:	0.05%
Covered Lines:	19706
Relevant Lines:	22072

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💛 - Coveralls