chore: [#3518] Remove public access modifier from generators, declarative, testing and schema

[sw-joelmut]

Addresses #3518
#minor

Description

This PR removes the public access modifier from all constructors, methods and properties for the generator-botbuilder, botbuilder-dialogs-declarative, botbuilder-testing and botframework-schema folders.

Note: These changes do not include the Typescript Constructor Shorthands (link).

Specific Changes

• Removes all public access modifiers from where it's declared under the generator-botbuilder, botbuilder-dialogs-declarative, botbuilder-testing and botframework-schema folders.

[coveralls]

Pull Request Test Coverage Report for Build 2258430918

• 8 of 8 (100.0%) changed or added relevant lines in 6 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.003%) to 84.48%

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Totals
Change from base Build 2245574340:	-0.003%
Covered Lines:	19902
Relevant Lines:	22310

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💛 - Coveralls