Add xml And xPath prebuilt function

[cosmicshuai]

Add xml and xPath pre-built functions to Adaptive-Expressions

xml and xPath can run in both browser and nodejs environment.

[coveralls]

Pull Request Test Coverage Report for Build 401152542

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.1%) to 84.696%

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Files with Coverage Reduction	New Missed Lines	%
libraries/adaptive-expressions/src/triggerTrees/node.ts	2	95.26%

Totals
Change from base Build 401147845:	-0.1%
Covered Lines:	17395
Relevant Lines:	19609

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💛 - Coveralls

[cosmicshuai]

Removed type definition of x2js package due to it use 'Omit' in index.d.ts. This only works for typescript version >= 3.5.0
This will cause yarn test:consumer failure.

"../../node_modules/@types/xml2js/index.d.ts(95,23): error TS2304: Cannot find name 'Omit'.\n",

[joshgummersall]

Just a quick ask to remove unnecessary private method JSDoc comments.