Export query interfaces method

[DanG100]

This change allows users of the library to access some of the ygot features directly from the query type.

Given that the interface types are all "getters" it seems safe to export these funcs.

[coveralls]

Pull Request Test Coverage Report for Build 2974798536

• 0 of 8 (0.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 88.51%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
ygnmi/types.go	0	8	0.0%

Totals
Change from base Build 2907820575:	0.0%
Covered Lines:	1533
Relevant Lines:	1732

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💛 - Coveralls

[wenovus]

Do all of the AnyQuery methods need to be exported? Or just a subset of them? I think keeping the public API small is a good idea if there is no need to export.

[DanG100]

Do all of the AnyQuery methods need to be exported? Or just a subset of them? I think keeping the public API small is a good idea if there is no need to export.

figure out a simpler way to do what i want, only need to export IsConfig() and IsSingleton, so that in lemming we can convert a state query to config query