port: [#5800] AdaptiveExpression Bool function is not very useful because it doesn't convert anything but ints (#6431)

[github-actions[bot]]

The changes in [#5800] AdaptiveExpression Bool function is not very useful because it doesn't convert anything but ints (#6431) may need to be ported to maintain parity with microsoft/botbuilder-dotnet.

Fixes #5800

Description

This PR updated the Bool built-in function to evaluate 'true' and 'false' strings as booleans using the Convert.ToBoolean() method.

Specific Changes

• Updated Function method of AdaptiveExpressions/BuiltinFunctions/Bool to evaluate strings using Convert.ToBoolean().
• Updated AdaptiveExpressions.Tests/ExpressionParserTests to evaluate bool('false') as false and added a new test case for bool('true')

Testing

This image shows the unit tests passing.

Please review and, if necessary, port the changes.