fix(Query): [Breaking] Return error for illegal math operations.

[rohanprasad]

If an operand is passed to math operations like log (ln, logbase), sqrt, pow which might result in illegal operation (resulting in NaN) we return 0 instead of an error. This PR fixes that.

Fixes DGRAPH-3150

Operation	Data type	Current behavior	New behavior
Add	Int64	Overflow/Underflow	Return error
Sub	Int64	Overflow/Underflow	Return error
Multiply	Int64	Overflow/Underflow	Return error
Pow	Float64	Fractional power of -ve number returns 0	Return error
Logbase	Int64	-ve number returns 0	Return error
Logbase	Int64	Log with base 1 returns large float	Return error
Logbase	Float64	-ve number return 0	Return error
Logbase	Float64	Log with base 1 returns large float	Return error
Ln	Int64	-ve number returns 0	Return error
Ln	Float64	-ve number returns 0	Return error
Negative	Int64	-ve of MinInt64 remains same	Return error
Sqrt	Int64	-ve number return 0	Return error
Sqrt	Float64	-ve number return 0	Return error

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This change is 

[CLAassistant]

All committers have signed the CLA.

[jarifibrahim]

Looks good to me. Defer to @ajeetdsouza for the final approval.

[ajeetdsouza]

Create a table with the old and new behaviours of all the math operations we've changed, and notify the docs team.

[NamanJain8]

Looks good to me.

Resolved issues