port: extend merge built-in function

[Danieladu]

Fixes #3857

Description

extend merge built-in function

Specific Changes

Originally, merge only accepts objects.
For example:
merge({}, {k1:'v1'}, {k2:'v2', k3:'v3'})

but sometimes the input is an array, and there is no way to convert the array into a list of objects.
The solution is to change the merge function to accept array type as well.

The logic is, if the item is array, merge its object children.

For example:
merge({k1:'v1'}, [{k2:'v2'}, {k3: 'v3'}], {k4:'v4'})

The second item is array, if we follows the previous practice, would get en error which shows the input only accepts "structure object", but not array. But now, you would get the right result:
{ ​"k1":"v1", ​"k2":"v2", ​"k3":"v3", "k4":"v4"}

But it should be noted that, the flatten operator would be applied for only once. If the array is nested, exception would be thrown too.

For example:
merge([{k1:'v1'}, {k2:'v2'}]) -> ok
merge([{k1:'v1'}, [{k2:'v2'}]]) -> the item of the array should be an object.

Doc change

add [Doc should change] mark

[coveralls]

Pull Request Test Coverage Report for Build 1013968478

• 22 of 23 (95.65%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.003%) to 84.344%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
libraries/adaptive-expressions/src/builtinFunctions/merge.ts	22	23	95.65%

Totals
Change from base Build 1013051675:	0.003%
Covered Lines:	19684
Relevant Lines:	22142

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💛 - Coveralls