Change AdaptiveExpressions pre-built classes from Public to Internal

[cosmicshuai]

closes: #2560
The classes in Built-in functions now are internal, except some general operation evalutor classes, like NumericEvaluator.
This is achieved by limiting the export statement in index.ts.

[coveralls]

Pull Request Test Coverage Report for Build 154954

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 82.946%

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Totals
Change from base Build 154951:	0.0%
Covered Lines:	14997
Relevant Lines:	17187

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💛 - Coveralls

[chrimc62]