Make IMemory interface follow the convention instead of returning tuple

[Danieladu]

fix: #3162

[coveralls]

Pull Request Test Coverage Report for Build 97205

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 1900 unchanged lines in 243 files lost coverage.
• Overall coverage increased (+0.3%) to 78.265%

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Files with Coverage Reduction	New Missed Lines	%
/libraries/Adapters/Microsoft.Bot.Builder.Adapters.Facebook/FacebookAdapterOptions.cs	1	86.67%
/libraries/integration/Microsoft.Bot.Builder.Integration.ApplicationInsights.Core/ApplicationBuilderExtensions.cs	1	71.43%
/libraries/Microsoft.Bot.Builder.AI.LUIS/LuisApplication.cs	1	96.36%
/libraries/Microsoft.Bot.Builder.AI.LUIS/V3/LuisApplication.cs	1	96.43%
/libraries/Microsoft.Bot.Builder.AI.LUIS/V3/LuisUtil.cs	1	96.35%
/libraries/Microsoft.Bot.Builder/BotStateSet.cs	1	85.0%
/libraries/Microsoft.Bot.Builder.Dialogs.Adaptive/Actions/BaseInvokeDialog.cs	1	87.5%
/libraries/Microsoft.Bot.Builder.Dialogs.Adaptive/Actions/Case.cs	1	87.5%
/libraries/Microsoft.Bot.Builder.Dialogs.Adaptive/Actions/EditActions.cs	1	93.75%
/libraries/Microsoft.Bot.Builder.Dialogs.Adaptive/Actions/EndTurn.cs	1	81.82%

Totals
Change from base Build 97159:	0.3%
Covered Lines:	13287
Relevant Lines:	16977

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💛 - Coveralls